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Biofloc technology in aquaculture: Beneficial effects and future challenges
... The development of system [5,27]. These clumps are composed of microorganisms such as heterotrophic and chemoautotrophic bacteria, cyanobacteria, archaea, viruses, microalgae, yeasts, and fungi [8]. Additionally, bioflocs can harbor or be inhabited by free-swimming invertebrates like rotifers, copepods, protozoa, cladocera, amoebas, ostracods, nematodes, and annelids [2]. ...
... The utilization of periphyton technology has been found to have multiple applications, including the removal of both inorganic and organic wastes, the natural augmentation of food production for cultivated species, and the improvement of water quality within culture [31]. In this technological context, stationary heterotrophic and autotrophic aquatic species, including fungus, protozoa, bacteria, phytoplankton, benthic organisms, zooplankton, and other invertebrates, are cultivated on submerged surfaces and utilized as naturally occurring nourishment for shrimp and fish communities [3,8]. The productivity of biomass of Periphyton is contingent upon the levels of light intensity and nutrient availability. ...
... In aquaculture, the application of these specific biofloc technology system techniques have demonstrated various levels of effectiveness in the removal of ammonia and solids, creation of biofloc, and overall improvement of aquaculture outputs [51]. Membrane biological reactors (MBRs) and sequencing batch reactors (SBRs) have been identified as effective methods for the removal of sediments and nutrients from effluents of culturing farms [8]. In general, the inclusion of carbon sources is necessary for the operation of SBRs, but MBRs do not require carbon supplements. ...
Given the scarcity of water and land resources, coupled with the competitive nature of aquaculture, the long-term viability of this industry will depend on strategies for vertical development. This involves enhancing production environments, increasing productivity, and advancing aquaculture technologies. The use of biofloc technology offers a potential solution to mitigate the adverse environmental impacts and the heavy reliance on fishmeal in the aquaculture sector. This method is designed to effectively assimilate inorganic nitrogen found in aquaculture wastewater, thereby enhancing water quality. Additionally, this process produces microbial protein, which can serve as a viable supplemental feed for aquatic animals. Furthermore, this technique has the potential to reduce the feed conversion ratio, thereby lowering overall production costs. This article provides an overview of the evolving field of biofloc system technology within aquaculture. In this study, we will examine the historical development and various types of biofloc systems, as well as the factors that influence their effectiveness. Finally, we will explore the economic potential of implementing biofloc systems in aquaculture.
... A greater variety of biofloc organisms can aid in enhancing the mineralization of waste flocs, [5,6], the consumption of protein [7], and controlling pathogens [8]. The meticulous development of a floc community in biofloc technology depends on several factors, such as the type of external carbon, environmental situations including oxygen levels, salinity, solids load, and light, the carbon to nitrogen (C/N) ratio, and the species being cultured [9]. ...
... Microorganisms associated with floc-forming extracellular polymeric substances exhibit adhesive properties, which facilitate the formation of cohesive flocs [15]. For a biofloc technology system to function effectively and to achieve its objectives, species from each category must be present, perform their respective roles, and engage in interactions with other species [9]. ...
In the modern era of Aquaculture, biofloc technology (BFT) systems have attained crucial attention. This technology is used to reduce water renewal with the removal of nitrogen and to provide additional feed. In BFT, microorganisms play a crucial role due to their complex metabolic properties. Pathogens can be controlled through multiple mechanisms using probiotics, which can promote host development and enhance the quality of the culture environment. During culturing in a biofloc technology system, the supplementation of microalgae and its accompanying bacteria plays a beneficial role in reducing nitrogenous compounds. This enhances water quality and creates favorable environmental conditions for specific bacterial groups, while simultaneously reducing the dependency on carbon sources with higher content. The fluctuations in the bacterial communities of the intestine are closely associated with the severity of diseases related to shrimp and are used to evaluate the health status of shrimp. Overall, we will review the microbes associated with shrimp culture in BFT and their effects on shrimp growth. We will also examine the microbial impacts on the growth performance of L. vannamei in BFT, as well as the close relationship between probiotics and the intestinal microbes of L. vannamei.
... Biofloc is a new aquaculture technology that has been developed to enhance water quality by balancing nitrogen and carbon in the system (Crab et al. 2012;Saha et al. 2022). It also has a dynamic nutritional value (Ekasari, Crab, and Verstraete 2010), such as 30.4% crude protein, 4.7% crude fat, 8.3% fiber, 39.2% ash, and 29.1% nitrogen-free extract (Ballester et al. 2010), and complete aquatic food source and supply bioactive compounds (Ahmad et al. 2017). ...
... Despite the high nutritional value, the wastewater from this system is a matter of concern due to the accumulated nitrate (Ahmad et al. 2017) and phosphorus (Emerenciano, Gaxiola and Cuzon 2013;Lima et al. 2021) compounds. On average, 75% of the feed-N and 50 to 70% of feed-P are released into the water (Crab et al. 2012;de Lima et al. 2019). Thus, studies related to nutrient removal and bioremediation of biofloc wastewater (BWW) are vital for the sustainability of aquaculture. ...
... In this context, intensive aquaculture systems are challenged by providing a favorable environment for high-density fish and shrimp production with little or no water exchange (Ray et al., 2010). Biofloc crops are increasingly common to meet such need (Avnimelech, 2007;Crab et al., 2007;De Schryver et al., 2008). Biofloc Technology (BFT) involves a closed system for the rearing of aquatic organisms based on nutrient recycling and conversion into microbial flakes, which serve as endogenous natural food for production animals (Azim and Little, 2008). ...
... As a result, the ammonia and nitrate concentrations in the culture media remain low (Hargreaves et al., 2007). Bio floc is made up of various beneficial microorganisms such as microalgae and zooplankton that are bound by organic particles, rather than bacteria (Crab, 2007). In the present experiment mean value of microbial floc density was found at the ranged from 25.0±0.00 to 26.35±1.91 ...
This experiment was conducted to optimize the stocking density of Nile tilapia (Oreochromis niloticus) in biofloc based farming system in tanks for a period of 90 days from 23 December to 22 March 2022 in Mohanpur upazilla, Rajshahi district, Bangladesh. The experiment was conducted in 5000 L cemented tanks (5m 3) under three different of stocking densities (T 1 : 200 fishes/m 3 , T 2 : 150 fishes/m 3 and T 3 : 100 fishes/m 3) having three replicates each. The initial weight of fish was 11.50±0.35 g and fishes were fed (34% protein content) twice a day @ 5-3 % body weight. Among three treatments, a significantly higher (P<0.05) average daily gain (ADG) of 1.15±0.07 g with specific growth rate (SGR) of 2.44±0.09 % day-1 were recorded in T 3 treatment but a significantly higher (P<0.05) average yield of 118907.70 and 114914.20 kg/ ha/3 months were obtained in T 1 and T 2 treatment, respectively. Higher average net benefit of 1231671.90 BDT/ha/3 months and BCR of 0.12 were obtained in T 2 treatment which is significantly higher (p<0.05) than T 1 and T 3 treatment. By an economical assessment, if the sales price is influenced by the final body weight, the reduced average harvest weight in higher stocking densities could lead to low profitability. Therefore, it is concluded that the use of intermediate stocking density, around 150 fishes/m 3 , has higher profitability since it produces a large proportion of harvested fish that reach high body weights, and possible high selling prices, combined with desirable biomass.
... For example, organic carbon, ammonia nitrogen, nitrites, nitrates, and phosphates are used as an energy source by oxidizing them into chemical forms and making them usable for algae, fungi, other bacteria, and filter feeders; they keep water quality and increase efficiency in the use of this resource by minimizing turnover rate, and at the same time, a source of complementary food is generated in situ for the cultivated species (Avnimelech, 2009;Correa et al., 2020;Crab et al., 2009;Ekasari et al., 2014;Hargreaves, 2013;Monroy-Dosta et al., 2013;Sgnaulin et al., 2020;Wasielesky et al., 2020). Bacterial populations are stimulated by modifying carbon: nitrogen ratio (C:N ratio) adding external carbon sources and providing sufficient aeration to keep the microbiota and nutrients suspended in the water column (Crab et al., 2012). Other benefits of BFT include the control of pathogenic bacterial populations. ...
... A C:N ratio of 10:1 was based only on the C:N content present in the commercial feed according to Emerenciano et al. (2013). The calculations proposed by Crab et al. (2012) were used, which, according to these authors, 75% of the N contained in the proteins provided in the feed ends up as residual N in the water column. The percentage of C in molasses and wheat was estimated at 28% and 31%, respectively, based on their carbohydrate content, while the estimated percentage was 23.5% in malted barley. ...
The present research evaluates the performance of the Nile tilapia (Oreochromis niloticus) (initial weight 11.5 ± 0.07 g) with biofloc technology. For this purpose, spent grains (malted barley) from the brewing industry after aerobic fermentation were used, as both a carbon source (suspended solids) and partial substitute for the diets at 0, 10, 20, 30, and 40% levels (settleable solids). The partial 20% substitution of the diet did not have significant effects on the biological parameters: final body weight, weight gained, average body weight, specific growth rate, daily growth index, condition factor, feed conversion ratio, protein efficiency rate, and viscerosomatic and hepatosomatic indices. However, the dietary substitution showed a significant effect on the final biofloc chemical composition. Nitrogen compounds, NH4⁺, NO2⁻, and NO3⁻, were adequate for tilapia cultivation in all the treatments. No clear effect of partial dietary substitution was observed on meat quality parameters: pH, color, water holding capacity, and amino acid and fatty acid profile of fillet. The results suggest that a 20% substitution of the diet for malted barley is suitable for satisfactory biological parameters and Nile tilapia fillet quality.
... BFT is an environmentally sound production system with minimal water exchange that maintains water quality through the assimilation of nitrogenous organic compounds by heterotrophic bacteria stimulated through a carbon-to-nitrogen balance, forming aggregates of microorganisms referred to as bioflocs. It also serves as an additional food source, thereby reducing the need for feed (Hargreaves, 2006;Crab et al., 2012;Emerenciano et al., 2021). BFT has gained prominence in the aquaculture field because it uses less water and land and produces less effluent discharge with a favorable benefit-cost ratio (Crab et al., 2012). ...
... It also serves as an additional food source, thereby reducing the need for feed (Hargreaves, 2006;Crab et al., 2012;Emerenciano et al., 2021). BFT has gained prominence in the aquaculture field because it uses less water and land and produces less effluent discharge with a favorable benefit-cost ratio (Crab et al., 2012). These factors favor the BFT expansion as a production system, nevertheless, clarification processes, carried out by gravity sedimentation, are routinely performed to maintain adequate levels of solids (below 500 mg/L) in the rearing system, as excess can lead to increase in biochemical oxygen demand, and hamper respiration due to gills clogging (Hargreaves, 2006;Gaona et al., 2011). ...
In Biofloc Technology (BFT), the disposal of solid waste represents a sustainability gap within. The presence of polyphenols in biofloc extracts has been reported, and these molecules have been widely explored for the synthesis of silver nanoparticles (AgNPs) in green nanotechnology. Polyphenols are employed to reduce silver ions and stabilize AgNPs. Compared to conventional methods (chemical synthesis), green synthesis makes the production of AgNPs sustainable and environmentally friendly by offering lower costs and avoiding the generation of hazardous waste that could impact the environment. This study proposes the extraction of polyphenols from bioflocs and their use as reducing and capping agents in the green synthesis of silver nanoparticles as a way to add value to the waste generated in BFT. Response Surface Methodology was used to obtain better extraction conditions by investigating the influence of four reaction variables (temperature, time, ethanol concentration, and solvent/solute ratios). The obtained extract was used to synthesize silver nanoparticles (BFAgNPs), which were used to determine the minimum inhibitory activity (MIC) and bactericidal activity (MBC) against Acinetobacter baumannii and Pseudomonas aeruginosa, as well as their anti-biofilm activity (inhibition and destruction) against A. baumannii. The highest polyphenol content was 1,918 µg gallic acid equivalents/g and the antioxidant activity was 1,278 µM Trolox equivalents/g for DPPH and 12,513 µM Trolox equivalents/g for ABTS. BFAgNPs exhibited an average diameter of 25.3 nm, as observed by transmission electron microscopy. Dynamic light scattering indicated a particle diameter of 123.2 nm, and polydispersity index (PDI) of 0.15. The zeta potential was measured at -22.5 mV. Fourier-transform infrared spectroscopy revealed distinct bands at 3616, 2924, 1682, 1532, 1234, and 1042 cm-1. BFAgNPs demonstrated MIC (38.8 µg/mL and 19.4 µg/mL for A. baumannii and P.aeruginosa), and MBC (77.5 µg/mL and 38.8 µg/mL for A. baumannii and P.aeruginosa) and antibiofilm activity, (47.3% inhibition and 27.8% destruction, respectively). It was concluded that the biofloc residue constitutes a source of polyphenols useful for the synthesis of AgNP with antibacterial capacity, thus representing a potential alternative for the waste valorization of BFT effluent.
... Despite being less toxic to aquatic animals than other nitrogen-containing compounds, high nitrate concentrations in ponds are still a concern. However, the incorporation of plants in integrated aquaponic culture systems can aid in the reduction of nitrate levels [34,35]. Data are a mean ± standard deviation. ...
The Aquaponic system has been widely implemented in various locations, primarily in freshwater environments, requiring adaptation to be compatible with saltwater ecosystems. The objective of this research is to explore the wastewater treatment capability of the Sonneratia caseolaris in a saltwater environment when applied to a recirculating aquaponic model for white-leg shrimp cultivation. The investigative process involves cultivation and determination of the water treatment coefficient of the Sonneratia caseolaris . The environmental parameters under scrutiny include NH 4 ⁺ , NO 2 ⁻ , NO 3 ⁻ , and total phosphorus per gram of plant biomass. Phase 1 consists of seedling production and model design; when the plants reach three months old, they will be tested with shrimp wastewater to assess their treatment capabilities. The results will provide parameters for operating the model in Phase 2. In Phase 2, the aquaponic model involves shrimp tanks (300 shrimp/1 m ³ ), fish tanks (50 fish/0.5 m ³ ), and the plant’s cultivation system. In Phase 1, the plant demonstrated treatment efficiencies of 90% for NH 4 ⁺ , 95% for NO 2 -, 32% for NO 3 ⁻ , and 27% for total phosphorus after 7 days. The treatment coefficients achieved were as follows (mg/g plants biomass): NH 4 ⁺ : 0.006, NO 2 ⁻ 0.005, NO 3 ⁻ 0.017, total phosphorus: 0.057. Transitioning to Phase 2, the results confirm that the aquaponic model, incorporating Sonneratia caseolaris for water recirculation in shrimp farming, is not only technically feasible for small-scale aquaponic models but also scalable for large-scale farm production. Furthermore, the leaves and fruits of Sonneratia caseolaris can serve as a supplementary herbal source for aquaculture species, enhancing the economic sustainability of the recirculating model.
... The consumption of bio ocs also has a probiotic effect, improving the health of the animal (Emerenciano et al. 2021). However, a disadvantage of BFT is the greater requirement of dissolved oxygen as a result of the greater demand for microorganisms in suspension in the water, as well as possible greater instability of the nitrogen compounds if the system is not properly managed (Crab et al. 2012). ...
The nursery phase in autumn is an important strategy for scaling up tilapia farming in subtropical regions, which otherwise suffers from a lack of fingerlings in winter. Tilapia nursery is carried out in a semi-intensive system in ponds; however, the biofloc technology system (BFT) has productive, environmental and health advantages. This study aimed to compare the production of Nile tilapia ( Oreochromis niloticus ) juveniles in two rearing systems during autumn through the evaluation of zootechnical, environmental, and hematological parameters, as well as production costs. In each system, four experimental units were used on a pilot scale and stocked with fingerlings with an average weight of 1.95 ± 0.32g. In the semi-intensive system, 25 m³ ponds were used, and each was stocked with 1,100 fingerlings (44 fish.m − 3 ). In the super-intensive system, 4 m³ circular tanks were used, each stocked with 2,200 fingerlings (550 fish.m − 3 ). The production of tilapia juveniles in BFT showed greater stability of water quality parameters throughout rearing in association with higher water temperature owing to the greenhouse. This allowed similar growth between fish in both systems, but with productivity 12.7x higher in BFT, while consuming 29.6x less water. Hematological parameters among fish in the two systems were also similar. Finally, BFT showed a lower total operating cost.
... Third, use biofloc technology (BFT). BFT has attracted attention recently, and is considered to be a sustainable and environmentally friendly aquaculture system (Crab et al., 2012;El-Sayed, 2021;Khanjani and Sharifinia, 2020). The main principle of BFT uses bacteria, algae, or protozoa in the water to absorb the waste nutrients and convert them into biomass, which then serves as natural food for the farmed species (Halim et al., 2019). ...
The Pacific white shrimp (Litopenaeus vannamei) plays a crucial role in global aquaculture, contributing significantly to farmed shrimp production, with China being a major contributor. In the last two decades, China's production of farmed L. vannamei experienced substantial growth due to expanded aquaculture areas and intensification. These processes can lead to increases in greenhouse gas emissions. However, the magnitude of greenhouse gas emissions from L. vannamei aquaculture systems remains unclear. Therefore, in this study, we systematically quantified greenhouse gas (carbon dioxide, methane, and nitrous oxide) emissions in L. vannamei farming systems with different levels of intensification. Various emission sources were assessed, including infrastructure, energy use, feed production, and pond aquatic emissions. The estimates indicate that greenhouse gas emissions increased from 6159.35 ± 475.24 kg CO 2 e/t of L. vannamei in semi-intensive systems to 24,059.81 ± 3846.31 kg CO 2 e/t of L. vannamei in super-intensive systems. The increase in greenhouse gas emissions was primarily due to energy use (2395% increase) and infrastructure (15,939% increase). As a result, the greenhouse gas emissions from China's shrimp farming industry increased threefold (from 5633.37 ± 177.40 to 19,730.68 ± 635.52 million kg CO 2 e) from 2003 to 2022, mainly contributed by coastal provinces. As the demand for high-quality aquatic products continues to increase, coupled with the urgent necessity to reduce greenhouse gas emissions, there is a crucial requirement to lower the emissions associated with each unit of L. vannamei production. The results of this study suggest that reducing fossil fuel use, improving feed efficiency, promoting biofloc technology, and integrated multi-trophic aquaculture systems may help to build climate-resilient sustainable aquaculture. List of abbreviations GHG greenhouse gas FCR feed conversion rate EF emission factors FAO Food and Agriculture Organization BFT biofloc technology IMTA integrated multi-trophic aquaculture
... The formation of bioflocs can be controlled by the growth rate of heterotrophic bacteria by adding organic carbon sources (Crab et al. 2012;Wei et al. 2020). These organic carbon sources used in BFT systems effectively reduce ammonia nitrogen concentrations, enhance bacterial community diversity (Deng et al. 2018), and exert distinct effects on microbial community structures within the water (Wei et al. 2016). ...
This study aimed to investigate the effects of different concentrations of fructooligosaccharide (FOS) instead of glucose (GLU) as the carbon source in the biofloc system. GLU was used as the carbon source in the control group, and 2.5%, 5.0%, 7.5%, and 10.0% FOS were used instead of GLU as the carbon source in experimental groups. Ammonium chloride was used the nitrogen source with a C/N ratio of 15. Bacillus subtilis was supplemented to promote biofloc formation. The results showed that the concentrations of ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, and total nitrogen were reduced effectively in all groups. High-throughput 16S rRNA sequencing revealed that the abundance of Flavobacterium was significantly increased in the 2.5% FOS group (P < 0.05), while Acinetobacter was significantly increased in the 10.0% FOS group on the 14th day (P < 0.05), the abundance of Aeromonadaceae was significantly reduced in all experimental groups (P < 0.05). Compared with the control group, the abundance of Aeromonadaceae was significantly decreased in 2.5% FOS on the 28th day (P < 0.05). Correlation analysis between microbial community composition and environmental factors indicated Flavobacterium and norank_f__norank_o__Saccharimonadales were negatively associated with three forms of nitrogen. In summary, the substitution of GLU with 2.5% FOS as the carbon source in the biofloc system significantly increased the abundance of core bacteria (Flavobacterium and Acinetobacter) and significantly reduced harmful bacteria (Aeromonadaceae), thereby stabilizing bacterial communities within the aquatic environment. The positive effects exhibited by 10.0% FOS were similar to 2.5% FOS. Based on experimental results and cost, the recommended proportion of FOS as a substitute for GLU is 2.5%. This research provides a foundation for the application of FOS as a carbon source in biofloc system and serves as a reference for future studies in this field.
... Biofloc technology recycle organic waste using microbial colonies into protein-rich feed for aquatic organisms, thus improving water quality and reducing environmental pollution (Emerenciano et al., 2017). The biofloc system has been successfully applied to various fish species, such as Nile tilapia (Emerenciano et al., 2017), and catfish (Liu et al., 2016) and shrimp (Crab et al., 2012), 20% reduction of feed costs (Emerenciano et al., 2012), promoting growth and improving fish health (Faizullah et al., 2019). ...
Nile Tilapia (Oreochromis niloticus) is the most common marketable fish species in biofloc throughout
the world. It has higher growth rate and is reared in limited resources when compared to other aquaculture
species. This research work identified the requirements needed for installation of biofloc setup in winter session;
different physico-chemical parameters and optimized the floc density for growth of Nile Tilapia (O. niloticus) in
the study area. A total of three tanks were taken and the floc concentration was 121.071g in tank first, 131.16g
in second and 135.19g in tank third. Total fingerlings (750) stocked were divided in three tanks (dimensions
of length was 15feet, height=4.5feet, water level=3.2 feet) with water volume of 17000 liters in each tank.
Formulated feed was used with 30% and 40% crude protein (CP) and buffalo meat. Water temperature was
maintained at 31o
C using heater (500Watts) with thermostat. The results were recorded with significant value
in the growth of fish during 4th to 9th weeks. The values of fish weight were recorded higher (P<0.05) in group
3 than the group 1 and group 2. The floc concentration, feed and physico-chemical parameters have positive
effects on biofloc system at winter session for quality production of Nile Tilapia (O. niloticus) production
... In BFT, a heterotrophic microbial community is developed by manipulating the relationship between carbon (C) and nitrogen (N) through the addition of an external source of organic carbon (Khanjani et al., 2023). This leads to the formation of bioflocs, which are aggregates of bacteria, microorganisms, excreta, and feed, that are consumed by the fish (Avnimelech, 2007;Azim;Little, 2008;Crab et al., 2009;Crab et al., 2012). However, just few studies have been developed comparing the use of the 17α-MT hormone during larviculture of Nile tilapia in biofloc and clear water systems. ...
We evaluated the use of the hormone 17α-methyltestosterone during the larviculture of Nile tilapia in biofloc and clear water systems. A completely randomized experimental design was adopted with four treatments and four replications: biofloc system without dietary hormone incorporation (BFT-D); biofloc system with dietary hormone incorporation (BFT-H); clear water without hormone incorporation in the diet (CLW-D); and clear water with hormone incorporation in the diet (CLW-H). The 28-day larviculture of Nile tilapia was carried out using 16 tanks with capacity of 15 L. The evaluations included water parameters, growth, survival, and gonad histology. The biofloc system displayed higher values for alkalinity, total suspended solids, settling solids, and turbidity compared to the clear water system (p < 0.05). Nevertheless, no difference (p > 0.05) was observed for in final weight, weight gain, feed conversion factor, survival, and growth rate between treatments. Then, tilapia post-larvae can be successfully reared in both biofloc and clear water systems without any negative impact on their zootechnical performance. Nonetheless, such results showed that tilapia can be reared in alternative systems, which can increase the production of this species.
... Moreover, culturing Nile tilapia at high density to increase production has been made possible using biofloc technology (Avnimelech, 1999;Assaduzaman et al., 2009;Fimbres-Acedo et al., 2020;Manduca et al., 2020;Khanjani and Sharifinia, 2020) Biofloc is a general term for the activated sludge which is adopted from the biological waste water culture system by maintaining adequate levels of oxygen, microorganisms, and C/N ratios (Avnimelech, 1999;Putra et al., 2019;Khanjani and Sharifinia, 2020) and also conserve water, thus minimizing environmental impacts (Manduca et al., 2020;Silva et al., 2022). The system is considered very cheap, simple, environmentally friendly and has very high productivity (Crab et al., 2012;Taw, 2014;Mohammadi et al., 2021). The formation of biofloc by microorganisms, especially heterotrophic bacteria, generally aims to increase nutrient utilization, avoid environmental stress, and predation (De Schryver et al., 2008;Mohammadi et al., 2021). ...
Addition of microalgae in the biofloc system may improve growth and survival of Nile tilapia. Also, culturing Nile tilapia in saline water biofloc system may be an adaptation for freshwater shortage. In this study, the growth and survival of Nile tilapia cultured in a low salinity biofloc system with added microalgae was investigated. Increasing salinity in the culture system was done by gradually adding sea water into acclimatization container (618 L, v) on weekly basis for 4 weeks until 9 psu salinity was reached. Tilapia were allowed to adapt to salinity change for one week and fed with commercial feed twice a day until satiation. The biofloc experiment was conducted with 3 microalgal density treatments (5, 15 and 25× 10 4 cells. mL-1) in triplicates. Average initial weight of experimental fish was 4.82±0.76 g. Tilapia were reared for 40 days in aquaria (35× 35× 40 cm, l× w× h, 15 L, v) containing 8 individuals fish in each aquarium. The commercial pellets were delivered twice per day at 5% of tilapia biomass until satiation. T. chui was added to the tilapia culture every week. This study showed that the addition of microalgae did not affect the fish weight gain, specific growth rate and survival (p> 0.05). However, feed conversion ratio and culture productivity were better in tilapia supplied with weekly addition of T. chui at 15× 10 4 cells mL-1 compared to other densities tested.
... There is a need to find sustainable solutions in producing fish. The demand for fish calls for the expansion and intensification of aquaculture production (Crab et al., 2012) and Ragasa et al., (2022). To grow sustainably, aquaculture must produce more fish per unit of land and water and reduce its reliance on wild-caught fish for feed. ...
The structure of microbial communities in a Biofloc Technology (BFT) system has a great influence on the optimal functioning of the system. This makes understanding the microbial composition in BFT of paramount importance. A study was conducted to characterize the microorganisms in an indoor biofloc technology system. The microorganisms were qualitatively and biochemically analyzed. Qualitative analysis of microorganisms in BFT was carried out using microscopy and plate culture of bacteria and fungi. Isolated bacteria were identified by colony morphology, gram staining and microscopic observation. Catalase test, as a biochemical test, was also used in identifying bacteria. Biochemical analysis of the bio floc was achieved through proximate analysis of nutrients following AOAC (2002) methods. The bio floc sample used in the present study was obtained from culture water of three 1000l circular fibreglass tanks with a working volume of 580l of bio floc water per tank. Oreochromis karongae fingerlings were stocked in the three tanks at a stocking density of 6kg/m3 per tank and cultured for 12 weeks. The fish were fed 30% CP on-farm formulated feed (2mm pelleted) with a feeding rate of 1.5% of the total estimated fish biomass. Maize flour was added in tanks to maintain an optimum C/N ratio (above 10) for heterotrophic bacteria production. Microscopy of the biofloc water revealed various types of microorganisms, which included Protozoa (e.g. ciliates), Zooplanktons (e.g. Rotifers and copepods) and nematodes, heterotrophic bacteria and fungi. It was noted that the bacteria were all heterotrophic bacteria, which confirmed their utilisation of organic carbon in the BFT system to produce microbial protein. The biochemical composition of biofloc showed that the nutritional quality of biofloc was appropriate for tilapia with the exception of lipid content, which was found to be (3.25%). This value is considered low for aquaculture feed as a range of 5- 10% lipid content in feed is recommended. BFT is a promising field which will enable aquaculture to grow towards an environmentally friendly approach because of the ability of microorganisms to recycle nutrients in the system.
... The pollutant nitrogenous compound in aquaculture system effluent produces an increase in the amount of chemical and biological oxygen demand in the water [2]. Furthermore, the high cost of water resources restricts aquaculture development due to the extensive use of water in the aquaculture system [3]. Furthermore, the growing price of the feed ingredient raises the expense of fish production [4]. ...
Aquaculture is one of the important food-producing sectors. However, the effluent of the aquaculture system consists of pollutants such as nitrogenous compounds and the ample usage of water for traditional aquaculture systems. Therefore, biofloc technology was developed in the aquaculture industry in the 1980s to improve the water quality of the system and increase the fish production. The purpose of this experimental work is to investigate the effect of biological factors on the growth performance of fish and the water quality of the biofloc technology (BFT) aquaculture system for red hybrid tilapia cultivation. In this study, 3 biological factors such as the carbon-to-nitrogen ratio, stocking density and the feeding rate were studied under BFT. Parallel experiments in thirteen suspended growth tanks were carried out within (10:1-20:1) C/N ratio, (1%-5%) feeding rate and (20-80 fish m ⁻³ ) stocking density for 10 weeks. Growth rate of fish and water quality data such as ammonia, nitrite and nitrate concentrations were collected weekly during the study. The results revealed that the 20:1 C/N ratio gave the best water quality. Feeding rate at 4% of body weight produced good growth performance of the tilapia species and the higher stocking densities lead to lower water quality and survival rate.
... This technology enables not only to improve water quality by decreasing toxic nitrogen compound but also to form a biofloc as nutrient source for fish. It is also possible to realize minimal or zero water exchange in aquaculture system and increase fish production [5][6][7]. ...
... Third, use biofloc technology (BFT). BFT has attracted attention recently, and is considered to be a sustainable and environmentally friendly aquaculture system (Crab et al., 2012;El-Sayed, 2021;Khanjani and Sharifinia, 2020). The main principle of BFT uses bacteria, algae, or protozoa in the water to absorb the waste nutrients and convert them into biomass, which then serves as natural food for the farmed species (Halim et al., 2019). ...
... This was added every twice in week. Amount of carbohydrate requirement (∆CH) for assimilate ammonium converted in microbial protein was calculated based on following the standard protocol of Avnimelech (1999) [3] and crab et al. (2012) [4] . This is slightly modified based on carbon content of molasses and protein content of feed used. ...
... Tacon et al. (2002), stated that the bacterial flocs contain high levels of protein and other important compounds that complement the shrimp nutrition. The presence of a high level of protein in bacterial flocs is relevant for shrimp, as protein is an essential nutrient for the healthy growth and development of these animals (Crab et al., 2012). The availability of a supplementary food source for shrimp is essential to meet their nutritional needs and promote good growth performance by reducing feed use. ...
... difference between the Biofloc groups, which included C/N 10:1, 15:1, and 20:1. Undoubtedly, the microbial communities of Bioflocs may be significantly impacted by the first injection of beneficial bacteria or natural biota [36] . A practical and efficient way to quicken the growth of Bioflocs in zero-exchange high density prawn culture systems is to inoculate culture water with Biofloc-enriched water and add specific sources of carbohydrates [8,37] . ...
... Lara, Krummenauer [5] recognize that biofloc aeration aims to provide oxygen beyond the inherent constraints in sustaining elevated stocking densities with high productivity, even distribution of dissolved oxygen in the water column, and to thoroughly oxygenate sediment coverage. Of late, there has been recognition of aeration influencing the aggregation and breakage of biofloc [7]. −(RTE) where C is the concentration of dissolved oxygen in water, k is Henry's Law constant (solubility coefficient), PO2 is the partial pressure of oxygen in the air, E is the activation energy for oxygen dissolution, R is the ideal gas constant, and T is the absolute temperature. ...
Biofloc Technology (BFT) is specifically designed to tackle critical challenges in aquaculture, including the reduction of excessive water usage, minimizing effluent discharge, optimizing nutrient utilization from feed, and strengthening overall biosecurity on farms. This innovative approach utilizes clusters of bacteria, algae, or protozoa within a matrix rich in particulate organic matter to enhance water quality, improve waste management, and control diseases. Given the system loading rates, there is a heightened need for elevated dissolved oxygen levels and optimal flow rates. Acknowledging the limitations of traditional aeration systems, this review hypothesizes employing fine bubbles as a panacea. The article, therefore, condenses information on fine bubble impacts in biofloc with a special focus on faster biofloc establishment, favorable microbial diversity, improved respiratory health, accelerated growth rates, optimized metabolism, improved feed conversion ratios, reducing costs, and enhanced overall aquatic health. The suitability of fine bubbles in diverse aquaculture environments is also explored with highlights on areas for further research to optimize and scale up fine bubble-fueled biofloc as an environmentally friendly aquaculture.
... Based on these results, household-scale whiteleg shrimp cultivation is feasible to develop in coastal areas. According to Crab et al. (2012), biofloc technology enhances water quality in aquaculture by balancing carbon and nitrogen in the system. The technology has recently gained attention as a sustainable method to control water quality, with the added value of producing proteinaceous feed in situ. ...
Bidayani E, Valen FS. 2023. Short Communication: Efficiency economic of whiteleg shrimp Litopenaeus vannamei (Boone 1931) cultivation with a household scale biofloc system. Indo Pac J Ocean Life 7: 156-160. Aquaculture is one of the necessary sectors for fisheries in Indonesia because it can contribute to national food security, income, employment development, and foreign exchange earnings. Shrimp is a non-oil and gas export commodity that plays a crucial role. Besides the high price, shrimp has a large market in various countries Whiteleg shrimp Litopenaeus vannamei (Boone 1931) cultivation is synonymous with large capital. However, with innovation, people can cultivate whiteleg shrimp in their yards with small capital. This study aims to analyze the business efficiency of a household-scale shrimp farming business with a biofloc system. The research method is a case study in the Bio Ebi Micro Fish Cultivator Group, Air Mawar Village, Air Itam District, Pangkalpinang City, Bangka Belitung Islands Province, Indonesia. Collecting data is observation and interviews; the data analysis method is descriptive. The study's results show the acceptance of cultivators per cycle is 172,800,000 IDR with an average production yield of 1.8 tons/cycle with a selling price of 96,000 IDR/kg. The efficiency of household-scale shrimp farming with a biofloc system is 2.39. Based on these results, household-scale whiteleg shrimp cultivation is feasible to develop in coastal areas.
... The kind and quantity of storage polymers and the flocs' overall composition are determined mainly by the organic carbon source [10]. Compared to conventional practices for farming fish species, BFT is more efficient regarding water and feed usage [11]. Various microbes and their cell components have been utilized as immunostimulants or probiotics to enhance fish growth, immunity, disease resistance, and antioxidant status [12]. ...
Biofloc technology (BFT) is one of the most sustainable aquaculture system, which is based on the principle of nutrient recycling and addition of carbon to enable heterotrophic microorganisms to the system. To evaluate the performance of the biofloc culture system for Cyprinus carpio fingerlings, a 60-day growth trial was conducted. The fingerlings (n = 600) of average body weight (4.92 g ± 0.14) were stocked in 12 circular fiberglass tanks (300 L, volume 10.59 cft) to form three biofloc treatments (T1, T2, and T3) along with one control group. The carbon sources for treatments were sugarcane molasses, tapioca, and wheat. The C/N ratio of 15 was maintained for all treatments. After 60 days of rearing, the fish were challenged with Aeromonas hydrophila, and the relative percentage survival (RPS) was observed over 14 days. A haematological, nonspecific immune, and stress parameters were analyzed using blood and serum samples collected at intervals of 20, 40, and 60 days. According to the results, the carbon sources affected the water quality parameters but were still adequate for fish welfare. An increased biofloc volume was observed with tapioca. Growth performance and better feed conversion ratio were recorded in biofloc with the tapioca group. The hematological parameters, including haemoglobin (Hb), hematocrit (HCT), white blood cells and lymphocytes were significantly ( P < 0.05 ) higher in biofloc-based tapioca group than in other treatments and control. Further, the serum protein, globulin, albumin, total immunoglobulin, and respiratory burst activity were also found significantly ( P < 0.05 ) higher in biofloc with tapioca as carbon source. However, the lysozyme activity was higher in biofloc with the wheat group. The RPS in tapioca was significantly higher, followed by biofloc with wheat. In conclusion, the tapioca-based biofloc can improve C. carpio growth, haematology, and nonspecific immune response under zero water exchange.
... Aquatic products' quality and safety cannot be guaranteed [6,11]. However, inducing disinfectants, probiotics, herbal medicines have limited effects of prevention and control of AHPND and hence cannot improve them [12][13][14][15][16][17]. Clarifying the mechanisms of the interaction of nanoparticles with V. parahaemolyticus is crucial for the development of disease prevention and control strategies and agents, and to reduce the mortality and economic in shrimp aquaculture. ...
In shrimp aquaculture, a major economic loss due to the bacterial disease called acute hepatopancreatic necrosis disease (AHPND) infected by Vibrio parahaemolyticus and caused the highest mortality (100%). Many approaches have been addressed to control vibriosis diseases in the shrimp industry, such as water monitoring and replacements, management practices and use of antibiotics but not fully controlled. V. parahaemolyticus has important virulence factors such as thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH), both are strongly directly associated with pathogenicity. Materials can be designed to specifically target PirA, PirB, TDH, and TRH, offering a targeted and effective approach to prevent infections in aquaculture. In the present study, in silico approach to unveil the potential of nanomaterials (ZnO, CuO, Se, and Fe2O3) as inhibitors against the toxins and thermostable proteins of V. parahaemolyticus has been studied via molecular docking analysis, AutoDock paired an empirical free energy force field with a Lamarckian Genetic Algorithm was used. The interaction results were visualized using molecular graphics tool Chimera. The current work is focused on predicting the ligands (ZnO, CuO, Se, and Fe2O3 nanoparticles) interact with the toxin and thermostable proteins of V. parahaemolyticus. The conformations of ligands bonded to macromolecular proteins can be assessed with the use of computational docking. These findings may be used to develop novel strategies for halting as well as controlling V. parahaemolyticus infections.
... Biofloc technology involves stimulating the proliferation of microorganisms in aquaculture by adding carbohydrates sources such as sucrose, cassava, glucose or cellulose into the water. This helps regulate the carbonto-nitrogen ratio (C/N ratio) to achieve optimal conditions with minimal water exchange (Crab et al, 2012). The presence of high C/N ratios in the culture system causes a transition in the dominant microbe population from autotrophic to heterotrophic, as seen in the study conducted by Browdy et al (2001). ...
The primary aim of this research was to investigate the disease conditions in freshwater fishes grown in a biofloc system in the Golaghat district of Assam. Out of the 92 fish samples analyzed, 50 fish were found to be severely infected with blue slime disease or Costiasis. The infected fishes exhibited clinical manifestations such as lethargy, irregular swimming patterns, erosion of the caudal fin and excessive mucus production. Additionally, a blue-gray or white or light pink film formed on their skin as a result of the disease condition which is a key characteristic of costiasis disease. The prevalence analysis indicated a high prevalence rate throughout the winter months, with December having the highest prevalence rate at 90%, followed by November at 59% and October at 20%. However, the disease was entirely eliminated in January through the implementation of water management strategies and bath treatment of disease infested fishes with 2 g/L with salt and 5 ppm potassium permanganate (KMnO 4). The water quality parameters pertaining to disease conditions include reduction in water temperature, dissolve oxygen, pH and increase in ammonia and nitrite levels which might be due to increase in stress condition. This study forms the basis for studying the disease prevalence in a biofloc reared freshwater fishes for which a comprehensive management strategy can be devised to ensure the long-term sustainability of the technique.
Biofloc technology converts toxic materials like Ammonia and Nitrates into proteinaceous substances which are very useful products for aquaculture. It’s a highly innovative and cost-effective technology in aquaculture systems which increases the production of fish/shrimp in a limited space by harnessing and re-circulating natural resources in a sustainable and eco-friendly way. Biofloc technology (BFT) uses bacterial biomass for the production of food for cultured species. Water recirculation, energy conservation, reduction of toxic wastes, and production of healthy species within a limited space are the key factors for sustainable agriculture. It enhances production and productivity by contributing to the supply of good quality fish juveniles, table fish, and shrimp. High stocking density leads to stress and increases the chance of infection but the floc with its diverse microbiome helps in reducing the mortality, morbidity and excessive use of antibiotics, which are a threat to the environment. Technologies like re-circulatory culture systems, pen and cage cultures and super-intensive aquaculture are now being highlighted due to their efficiency in utilizing space, feed and fresh water and also for allowing continuous monitoring of the culture systems. This technology is also essential in supplementing aquaculture farms with raw materials that use fish oil and fish protein in the fish meal to enhance production. This, in turn, reduces infections and increases the output. With the growing pressure of supplying nutritious food for people and increasing the GDP of every country, BFT can be a plausible solution. BFT culture can create employment. Government intervention can also help to provide subsidies for the procurement of essential requisites for cultural practice. This will help to boost the economy and create awareness and employment, without exploiting the natural resources in the rural areas.
The shrimp aquaculture industry has grown significantly recently, with a notable shift towards more intensive and super-intensive farming practices. While this intensification offers increased production and economic benefits, it raises concerns about energy usage and environmental impact. Aeration systems are crucial in shrimp aquaculture, particularly in intensive and super-intensive setups. However, the operation of mechanical aerators requires substantial energy input. Additionally, intensive shrimp farming can result in wastewater containing high levels of pollutants, posing a threat to the surrounding ecosystem if not appropriately managed. To address these challenges, there has been a focus on implementing advanced technologies in aeration and wastewater management within shrimp farming. These technologies aim to minimize energy consumption and mitigate the environmental impacts. This review highlights recent advanced technologies for aeration and wastewater management in shrimp farming, helping practitioners make informed decisions about adopting innovative approaches. Furthermore, this review provides insights into the perspectives of aeration and wastewater treatment technologies, offering guidance to farmers on selecting the most suitable techniques based on their specific practices. By embracing sustainable approaches to aeration and wastewater management, shrimp farmers can contribute to the industry's long-term viability while minimizing its ecological footprint.
This study aimed to evaluate the effect of the biofloc technology (BFT) system and the replacement of fish meal with Spirulina biomass on productive performance, intestinal histomorphometry, plasma biochemistry, and oxidative stress of Nile tilapia juveniles (Oreochromis niloticus) fed suboptimal levels of protein. Two factors were evaluated: production systems (clear water × BFT) and replacement of fish meal with Spirulina (0, 33, 66 e 100%). The design was in a 2 × 4 randomized factorial scheme with four replications, and the fish were evaluated for 48 days. Four isoproteic (28% crude protein) diets were formulated with gross energy values close to 4300 kcal kg⁻¹. Nile tilapia juveniles (0.23 ± 0.01 g) were distributed in 16 circular tanks (70 L) at seven fish/tank. The diets were formulated with protein levels approximately 20% below that required for the species and life stage. No interaction was observed between the factors evaluated (production systems × Spirulina inclusion). Rearing the fish in the BFT system avoided the adverse effects of diets with suboptimal protein levels on performance, intestinal histomorphometry, and protein metabolism. Lower values lower lipid peroxidation and higher antioxidant capacity were observed in fish reared in the BFT system, showing evidence of improvements in antioxidant responses and lower levels of physiological oxidative stress. Spirulina completely replaced fish meal in the diets of Nile tilapia juveniles without adverse effects on intestinal morphometry, protein metabolism, and antioxidant response. Replacing 66% of fish meal with Spirulina improved the productive performance, regardless of the rearing system.
Aquaculture has experienced significant global expansion and is considered one of the fastest-growing sectors in food production. However, there exist additional challenges that restrict the capacity to achieve maximum efficiency in aquaculture systems, such as issues over water quality and shortages of appropriate live feeds. Intensive aquaculture systems involve the use of protein-rich prepared feed for feeding the cultured animals. This may give rise to the discharge of nitrogenous compounds into the water, which can pose a risk to the environment when present in excessive quantities beyond the acceptable levels. In recent years, an innovative method called biofloc technology (BFT) has become a practical solution to this issue. Undoubtedly, BFT offers a groundbreaking method for nutrient disposal that eradicates the requirement for excessive water use or equipment maintenance. Three primary types of microorganisms are crucial in alleviating the adverse impacts of nitrogen compounds in this technique. Photoautotrophs participate in the processes of removal and absorption, whereas chemoautotrophs promote nitrification and conversion. Heterotrophs contribute to the absorption process. Biofloc predominantly consists of heterotrophic bacteria, alongside algae, protozoa, rotifers, and nematodes. While there have been reviews carried out on multiple aspects of biofloc technology, there exists a lack of literature that tackles this particular field of research progress. This article discusses every aspect and techniques of biological management used for removing nitrogenous waste compounds in biofloc aquaculture systems.
Intensive BFT (Biofloc Technology) system production leads to large amounts of FSW (Floc Solid Waste), but the disposal of this waste is rarely noticed. As one of the novel solid wastes of aquaculture, the FSW was treated through planting within various supplemental dosages to obtain a more comprehensive assessment on its reclamation potential in this experiment. FSW was added to the soil in the following proportions respectively: 0.5% (adding FSW/Soil weight ratio percentage W/W (dry matter/dry matter)), 1%, and 2%. Pure soil was selected as the control and the pot experiment was conducted based on Crown daisy (Glebionis coronaria (L.) Cass. ex Spach) for 40 days. FSW addition considerably increased soil fertility which exhibited the positive correlation except for the soil pH. Adding ratio with 0.5%, and 1.0% provided the best plant growth with the yield of 50.2 g/m2, and 41.5 g/m2 respectively. 2.0% FSW addition inhibited the growth of plants, while certain amount of FSW addition not greatly promoted the quantities of plants. FSW addition obviously altered the original soil rhizobacteria communities and increased abundance of some beneficial bacteria, especially for Bacillus sp, Fictibacillus sp. Through RDA (Redundancy Analysis), the strongly positive relation between soil fertility and functional microorganisms in FSW added treatments has been verified. In conclusion, positive plant growth performance and the facilitation of soil fertilities demonstrated the potential of FSW as soil fertilization and amendments.
This study evaluated potential for rearing the matrinxã, Brycon amazonicus , under different crude protein (CP) levels, using production performance, water quality and animal welfare as indicators. To achieve this, 720 juvenile fish (3.65 ± 0.17 g) were distributed across 24 experimental units (200 L) and fee study lasted 60 days. The study followed a factorial design (2x4), with two production systems: Biofloc technology (BFT) and clear water (CW), and four levels of crude protein (CP = 24%, 30%, 36%, and 42%) in the diet, with three repetitions for each. The study found that the BFT system showed a lower total ammonia level. However, the production system did not have any effect on pH or nitrite concentration. Oxygen levels were found to be lower in the 42% CP group. Fish produced in the BFT exhibited better performance of apparent feed conversion, productivity, and survival. The production system affected total leukocytes and neutrophils in the blood. There was no significant difference in carcass crude protein content and the ether extract content was higher in the animals from the BFT system. Nutritional composition of the biofloc showed differences for ash, with lower levels in the 42% CP treatment. In conclusion, juvenile matrinxã can be fed a diet containing 30% CP in both production systems. Furthermore, the results demonstrated that biofloc did not confer a direct benefit to matrinxã juveniles in terms of their feeding, however BFT represented a promising alternative for increasing the survival and improved animal welfare during the rearing phase.
Nitrogenous waste is a global concern in aquatic ecosystems. In the shrimp farming system, feeding is the main input of nitrogen, which leads to the accumulation of nitrogenous waste, such as ammonia, nitrite, and nitrate. Nitrogen cycling is crucial for nitrogenous waste removal and for the stability of the aquaculture system. Under the action of different functional microorganisms, a variety of nitrogen cycling pathways can be used for the transformation and removal of nitrogenous waste. Understanding the complexity of the nitrogen cycle is necessary for improving the aquaculture environment. This review examines the many components and mechanisms involved in the nitrogen cycle in shrimp farming system, including nitrification, denitrification, anammox, heterotrophic assimilation, and autotrophic assimilation. Because of the difference in aquaculture characteristics, nitrogen cycling pathways in different shrimp culture modes are diverse. The current application of the nitrogen cycle in shrimp farming system, including the outdoor pond mode and indoor industrialized mode, was presented in combination with the requirements for dissolved oxygen (DO), organic matter, carbon–nitrogen ratio, light, and other environmental factors. Overall, nitrification, heterotrophic assimilation, autotrophic assimilation, and heterotrophic denitrification are the main nitrogen cycle processes in the shrimp culture system. According to the characteristics of aquaculture modes and microorganisms, utilizing different nitrogen cycle processes can enhance the efficiency of the nitrogen cycle, facilitate the elimination of nitrogenous waste, optimize the aquaculture water environment, and improve overall aquaculture benefits.
In this thesis project, the effects of synbiotic and biofloc meal on the growth performance, gut microbiota diversification, proximate body composition, total gut bacterial counts, liver and intestinal histomorphology of Nile tilapia (Oreochromis niloticus) cultured under different salinities were examined. Tilapia with an initial weight of 21,52 ±2,21 g was divided into three main groups (freshwater 0 ppt, brackish water 6 ppt and marine water 18 ppt) each with triplicates of control and synbiotic groups. While the control groups were not supplemented with any feed additives, a single dose of combined dietary synbiotics and biofloc meal (Probiotic mixture for 1 kg of feed (Lactobacillus plantarum 10 ml 1.5x109 cob/g, Saccharomyces boulardii 250 mg 5x109 cob/g and Lactobacillus acidophilus 25 mg 5x109 cob/g), MOS as prebiotic (2 g/kg feed) and biofloc meal (3 g/kg feed)) has been added to the tilapia feeds of all the experimental groups in this study. At the end of the experiment, the highest final body weight (42.70±3.25 g) and weight gain (21.79±5.07 g) as well as the lowest FCR (1.17) were found in the freshwater group fed with synbiotic and biofloc meal added feeds. The lowest final body weight (37.13±5.79 g) and weight gain (15.65±6.00 g) and the highest FCR (2.00) were also recorded in the marine water control group. Unlike the growth performance, which decreased with the increase of water salinity, there was no significant difference between the groups cultured under different salinities in terms of gut microbiota, proximate body composition, total gut bacterial counts, liver, and intestinal histomorphology.
A 56-day experiment was undertaken to assess the influence of water changing frequency on the water quality, growth performance and physiological status of African catfish, Clarias gariepinus juveniles. There were three treatments with different water changing regimes, every two days, every four days and once a week. Nine plastic tanks were stocked with ten African catfish (10.39±0.36 g) each in triplicates for the three treatments. The fish were fed at 5% body weight daily. Selected water quality parameters were examined twice a week, while growth performance and physiological parameters were measured at the end of the eight weeks. pH, temperature and nitrate-nitrogen were not different-significantly among the treatments. The highest total ammonia-nitrogen (0.55±0.01 mg L 1) was observed in the treatment with water changes once a week, and it was significantly higher than the treatment with water changes every two days. Both total dissolved solids and electrical conductivity were also different among the treatments. Growth performance improved with decreased frequency of changing water; weight gain, specific growth rate and yield were all higher significantly in the treatment with water changes once in a week compared to every two days. Nutrient utilization, survival and body indices were not different significantly among the treatments. Higher glycogen and healthier livers were noted in the treatment with water changes once a week. The result established that-3 changing the water once a week for fish stocked up to 20 Kg m may confer more advantages on the fish and lead to improved performance.
Conventional aquaculture (ACUA-C) in Mexico is an activity that maintains an annual growth rate of 6%. Tilapia (Oreochromisniloticus) aquaculture is the predominant one in the country with 4,623 farms, where most of them operate with semi-intensive (SSI) and extensive (SE) production systems.
and extensive (SE), discharging wastewater without treatment, with a
treatment, with a negative impact on the environment. To mitigate this, new eco-technologies such as Biofloc (TBF), recirculation systems for aquaculture (RAS), constructed wetlands (HC) for wastewater treatment (HC) for water treatment and aquaponics (AC) are emerging to mitigate environmental environmental impacts of aquaculture. The objective of this work is to evaluate the feasibility of tilapia farming with TBF, RAS, HC and AC ecotechnologies through an economic and financial feasibility analysis, considering their environmental and social implications for a farm aquaculture farm Mexican aquaculture farm.
Chitosan (CH) shows great potential as an immunostimulatory feed additive in aquaculture. This study evaluates the effects of varying dietary CH levels on the growth, immunity, intestinal morphology, and antioxidant status of Nile tilapia (Oreochromis niloticus) reared in a biofloc system. Tilapia fingerlings (mean weight 13.54 ± 0.05 g) were fed diets supplemented with 0 (CH0), 5 (CH5), 10 (CH10), 20 (CH20), and 40 (CH40) mL·kg −1 of CH for 8 weeks. Parameters were assessed after 4 and 8 weeks. Their final weight was not affected by CH supplementation, but CH at 10 mL·kg −1 significantly improved weight gain (WG) and specific growth rate (SGR) compared to the control (p < 0.05) at 8 weeks. Skin mucus lysozyme and peroxidase activities were lower in the chitosan-treated groups at weeks 4 and 8. Intestinal villi length and width were enhanced by 10 and 20 mL·kg −1 CH compared to the control. However, 40 mL·kg −1 CH caused detrimental impacts on the villi and muscular layer. CH supplementation, especially 5-10 mL·kg −1 , increased liver and intestinal expressions of interleukin 1 (IL-1), interleukin 8 (IL-8), LPS-binding protein (LBP), glutathione reductase (GSR), glutathione peroxidase (GPX), and glutathione S-transferase (GST-α) compared to the control group. Overall, dietary CH at 10 mL·kg −1 can effectively promote growth, intestinal morphology, innate immunity, and antioxidant capacity in Nile tilapia fingerlings reared in biofloc systems.
Microorganisms, which are present ubiquitously in the earth, play a very important role in maintaining any kind of an ecosystem and aquatic ecosystems are no exception from it. These ecosystems are often prone to pollution and contamination by toxic and heavy metals, excess of nutrients (eutrophication), pathogens, foreign species, etc. which needs to be abated to keep it healthy. Also, to maintain the balance of an ecosystem, the nutrients must be recirculated and support for survival of the living organisms is required. These tasks are done by the microbial interactions with the pollutants and other organisms by taking different forms like biofilms and aggregates by employing various mechanisms like bioremediation (plant–microbe interactions), co-metabolism, etc. The microbes also decay the organic compounds which are generally applied to the fields thereby regulating the organic carbon, carbon dioxide and oxygen flow in the system. The microbes are one of the sole players responsible for fixing and regenerating the key organic elements like carbon, nitrogen, sulphur and phosphorous and mobilising the cofactors and vitamins necessary for metabolism, growth, and development of biological units. They are crucial for sustaining the food chains and food webs and thus regulate the energy and material fluxes. Functionally, these microbes support the living part of aquatic ecosystem and keep up the water quality. As a result of the associated interactions, they receive substances and services essential for their own survival and development which will be reviewed further in this chapter.
Kegiatan “Budidaya Lele Berbasis Teknologi Bioflock pada Kelompok Pembudidaya Ikan Mandiri Sentosa di Kecamatan Jati Agung Lampung Selatan" merupakan kegiatan transfer teknologi kepada masyarakat, yang sejalan dengan salah satu visi LPPM Unila. Pada kegiatan ini akan didiseminasikan teknologi bioflok dalam kegiatan budidaya ikan lele. Teknologi bioflok dalam budidaya perikanan menerapkan prinsip asimilasi nitrogen oleh bakteri heterotrof melalui modifikasi rasio C/N dalam air. Sasaran dari program ini adalah mitra kelompok pembudidaya ikan (pokdakan) Mandiri Sentosa di Kecamatan Jati Agung, Lampung Selatan. Program ini memiliki tujuan; 1) Pemahaman kelompok mitra dalam menggunakan teknologi bioflock sebagai solusi pengelolaan kualitas air budidaya ikan, serta 2) Membangun kemitraan dan kerjasama yang efektif antara perguruan tinggi dengan kelompok masyarakat di Kecamatan Jati Agung. Metode yang digunakan meliputi survei, pelatihan, denplot teknologi bioflock, pendampingan, dan evaluasi keberhasilan program. Kegiatan pengabdian kepada masyarakat ini terbagi menjadi 2 tahap yaitu tahap persiapan dan tahap pelaksanaan. Tahap persiapan meliputi: survei lokasi, sosialisasi kepada mitra, dan persiapan perlengkapan. Sedangkan tahap pelaksanaan meliputi: pelatihan budidaya ikan lele dengan teknologi bioflock, penyerahan paket teknologi bioflock, dan evaluasi kegiatan. Berdasarkan kegiatan pengabdian yang sudah dilakukan maka dapat disimpulkan bahwa adanya peningkatan pemahaman mitra mengenai penerapan teknologi bioflok hingga 100%, adanya manfaat yang diperoleh mitra melalui pelatihan budidaya ikan lele menggunakan teknologi bioflok, serta terciptanya kemitraan dan kerjasama yang efektif antara perguruan tinggi dengan kelompok masyarakat di Kecamatan Jati Agung, khususnya kelompok mitra Mandiri Sentosa.
Biofloc technology (BFT) has gained popularity recently as the aquaculture industry faces significant economic losses due to water pollution creating various pathogens. Many bacterial, viral and fungal diseases in fish cause a decrease in annual world fish production. Therefore, owing to a growing demand for healthy fish, zero‐water exchange is widely practiced in fish and shellfish production. It minimizes the release of aquaculture wastewater into the aquatic ecosystem, which contains nutrients, organic matter and pathogens. It uses a minimal amount of land, which provides an impartial cost–benefit ratio to maintain socio‐economic sustainability. Besides sustainability, fish cultured in the BFT have also expressed better health status after being challenged by different pathogens. However, this review explores the use of BFT as a sustainable approach to wastewater utilization and fish and shellfish production. Apart from this, the review highlights the potential of BFT to enhance fish production in aquaculture systems and discusses various factors that affect the performance of systems, such as carbon‐to‐nitrogen ratios, aeration and the use of probiotics. It also investigates the role of biofloc in improving water quality, fish and shellfish health prophylactic properties, and its effect on gut microflora. The review further examines the economic feasibility of BFT and discusses about the cost‐effectiveness of implementing systems and the potential for generating additional revenue through the sale of bioflocs as a value‐added product. Overall, this review highlights the potential of BFT as a sustainable solution for wastewater utilization and increasing fish production. It provides valuable insights into the factors affecting the performance of BFT systems and suggests areas for further research and development in this field.
This study assessed the effectiveness of a solar-powered sediment lifting device (SSLD) in a fish pond. The experiment was conducted by installing the SSLD in a pond with silver barb (Barbonymus gonionotus) for50 days. The study showed that total ammonia nitrogen and nitrite in the pond without the SSLD were significantly higher than in the pond with the SSLD (p < .05). The total nitrogen, total phosphorus, total organic matter, and total organic carbon in the sediments, were significantly higher in the pond without the device than in the pond with the SSLD (p < .05). Weight gain and daily weight gain of the fish in the pond with the SSLD were higher than in the pond without the device (p < .05). This experiment revealed that installing the SSLD in fish pond culture decreases total organic matter in the water and sediments of the pond.
KEYWORDS: Sediment lifting devicepond aquaculturewater qualitysolar energysilver barb (Barbonymus gonionotus)
Future development of intensive aquaculture must deal with its impacts on the environment in the form of water pollution and the use of fish oil and fish meal. The bioflocs technology simultaneously addresses both problems co-occurring with the further expansion of the industry. While maintaining good water quality within the aquaculture systems it produces additional feed for the cultured animals. In contrast to conventional water quality control techniques, the bioflocs technology offers a sustainable, economical and easy-to-implement alternative. Chapter 1 gives an overview of the literature concerning nitrogen removal techniques in aquaculture and bioflocs technology.
In Chapter 2, the impact of the carbon source on the performance of biofloc reactors was studied. The carbon source influenced the capacity of the technique to control the water quality in the biofloc reactors and the nutritional properties of the flocs. The carbon source also affected the eukaryotic and prokaryotic community composition of the bioflocs, which offers great possibilities for fine-tuning of the technique, more specifically concerning water quality control, feed production and/or costs.
This prime importance of the choice of carbon source was confirmed in two further studies (Chapter 3 and Chapter 4) in which bioflocs grown on different substrates were fed to giant freshwater prawn (Macrobrachium rosenbergii) postlarvae and white shrimp (Litopenaeus vannamei), respectively. In both studies, glycerol-grown bioflocs showed better results than glucose-grown bioflocs. The potential significance of these results calls for further studies on the use of bioflocs as a feed in aquaculture, both in freshwater and saline systems. Parameters to consider in the future are accessibility, palatability or attractiveness of the bioflocs towards the animals, amino acid composition, essential fatty acids content and cost of the used carbon source as well as the overall cost of the technology (especially compared to conventional biofilter systems and feeding costs).
In addition to the environmental, economical and sustainable considerations addressed above, a more specific problem was studied in Chapter 5, where aquaculture animals are exposed to lower temperatures during winter, possibly leading to mass mortality in industrial ponds. Covering the ponds with either plastic sheets or glass allowed solar heating of the culture water (thereby reducing the temperature decrease) and permitted to minimize water exchange. The application of bioflocs technology resulted in maintenance of good water quality, concomitantly providing additional feed to the animals, tilapia (Oreochromis niloticus x Oreochromis aureus) without compromising survival, growth and condition factor of the cultured species.
At this moment, the aquaculture industry is most importantly faced with mass mortalities due to infectious diseases. To conclude this work, a potential extra added value feature of the bioflocs technology was studied in Chapter 6. In this study, bioflocs were found to be able to protect brine shrimp (Artemia franciscana) larvae from pathogenic Vibrio harveyi. These results indicate that in addition to water quality control and extra in situ feed production, the technique also has potential to protect the cultured animals from infections with pathogenic bacteria, which are responsible for major economic losses in aquaculture.
To conclude, the last chapter (Chapter 7) provides a brief discussion of the performed studies. Directions for future in depth studies are raised based on the studies performed in this work that might contribute to further sustainable development of aquaculture.
Global production of farmed fish and shellfish has more than doubled in
the past 15 years. Many people believe that such growth relieves pressure
on ocean fisheries, but the opposite is true for some types of aquaculture.
Farming carnivorous species requires large inputs of wild fish for feed. Some
aquaculture systems also reduce wild fish supplies through habitat modification,
wild seedstock collection and other ecological impacts. On balance, global
aquaculture production still adds to world fish supplies; however, if the
growing aquaculture industry is to sustain its contribution to world fish
supplies, it must reduce wild fish inputs in feed and adopt more ecologically
sound management practices.
A feeding experiment was conducted to determine the effect of the feeding attractant, glycine betaine (betaine hydrochloride) on the growth and feed conversion of juveniles of Macrobrachium rosenbergii (deMan) (mean initial weight 1.12 g). Three types of diets were prepared with the incorporation of glycine betaine at 5, 10 and 15 g kg−1 levels along with an unsupplemented control. After 60 days, weight gain, feed intake and food conversion ratio (FCR) were higher in prawn fed the three glycine betaine-added diets compared with the control feed. Among the glycine betaine-added diets, prawn fed glycine betaine at 5 g kg−1 level showed highest weight gain (2.73 g) by registering 61.5% increase in growth over control and also higher feed intake (5.79 g) and good FCR (2.12). There were highly significant differences (P < 0.01) in weight gain, feed intake, per day growth and FCR among treatments. There was no significant difference (P > 0.05) in survival among treatments.
A 15-day lab-scale experiment was performed to determine the possible use of bioflocs as a feed for Macrobrachium rosenbergii postlarvae. The bioflocs were grown on acetate, glycerol and glucose. A glycerol-fed reactor was initially inoculated with a Bacillus spores mixture. The highest protein content was obtained in the (glycerol+Bacillus) bioflocs, i.e. 58±9% dry weight (DW). The glycerol and acetate bioflocs showed a lower, but similar content (42–43% DW) and glucose bioflocs contained 28±3% DW. Higher total n-6 fatty acid contents were observed in the glycerol and (glycerol+Bacillus) bioflocs. The vitamin C content was variable, up to 54 μg ascorbic acid g−1 DW in the glycerol bioflocs. Bioflocs were fed to M. rosenbergii postlarvae as the sole feed. High survival levels were obtained in the (glycerol+Bacillus) and glucose groups, i.e. 75±7% and 70±0% respectively. This was significantly higher than the starvation control (0% survival after 15 days). This indicated that the prawns were able to feed on the bioflocs. These results are in accordance with the biofloc's nutritional parameters and suggest that the choice of the carbon source used for growing bioflocs is of prime importance.
The present research investigated the effect of carbon/nitrogen ratio (C/N ratio) control in ponds with or without substrate addition for periphyton development on production of giant freshwater prawn. C/N ratios of 10, 15 and 20 were investigated in 40 m(-2) ponds stocked with 2 prawn juveniles (5.023 +/- 0.02 g) m(-2) with or without added substrates for periphyton development. The various treatment combinations of C/N ratio and periphyton substrate addition are abbreviated as 'CN10', 'CN15', 'CN20', 'CN10+P', 'CN15+P' and 'CN20+P', P representing periphyton substrate. A locally formulated and prepared feed containing 30% crude protein with C/N ratio-10 was applied. Tapioca starch was used as carbohydrate source for manipulating C/N ratio and applied to the water column separately from the feed. Increasing the C/N ratio from 10 to 20 reduced (P<0.001) the total ammonia-nitrogen (TAN), nitrite-nitrogen (NO2-N) and nitrate-nitrogen (NO3-N) in water column and total Kjeldahl nitrogen (TKN) in sediment. The addition of substrates only influenced the NO2-N concentration in the water column (P<0.001). Increasing the C/N ratio raised the total heterotrophic bacterial (THB) population in the water column, sediment and periphyton (P<0.001). It also increased the dry matter (DM), ash free dry matter (AFDM), and chlorophyll a content of periphyton (P<0.001). The lowest specific growth rate (SGR), the highest food conversion ratio (FCR), and the lowest protein efficiency ratio (PER) were recorded in treatment CN10 (P<0.05). The addition of substrates did not influence size at harvest (P>0.05) but improved the survival from 62.8 to 72% (P<0.001). Increasing the C/N ratio from 10 to 20 increased the net yield by 40% and addition of substrate increased the net yield by 23%. The combination of C/N ratio control and substrate addition increased the net yield by 75% from 309 (CN10) to 540 (CN20+P) kg ha(-1) (120 days)(-1). This 75% higher production concurred with (1) a lower inorganic nitrogen content in the water column, (2) a higher THB abundance supplying additional single cell protein to augment the prawn production, and (3) an improved periphyton productivity and quality.
Rising global demand for seafood and declining catches have resulted in the volume of mariculture doubling each decade, a growth expected by the FAO to persist in the decades to come. This growth should use technologies with economical and environmental sustainability. Feed accounts for about half the cost in current high-volume fed mono-species aquaculture, mainly fish net pens or shrimp/fish ponds, yet most of this feed becomes waste. The resulting environmental impact and rising feed costs therefore hamper further growth of such farms. As in certain traditional polyculture schemes, plants can drastically reduce feed use and environmental impact of industrialized mariculture and at the same time add to its income. These nutrient-assimilating photoautotrophic plants use solar energy to turn nutrient-rich effluents into profitable resources. Plants counteract the environmental effects of the heterotrophic fed fish and shrimp and restore water quality. Today's integrated intensive aquaculture approaches, developed from traditional extensive polyculture, integrate the culture of fish or shrimp with vegetables, microalgae, shellfish and/or seaweeds. Integrated mariculture can take place in coastal waters or in ponds and can be highly intensified. Today's technologies are well studied and documented. They are generic, modular and adaptable for several culture combinations of fish, shrimp, shellfish, abalone, sea urchin and several species of commercially important seaweeds and vegetables. A 1-ha land-based integrated seabream–shellfish–seaweed farm can produce 25 tons of fish, 50 tons of bivalves and 30 tons fresh weight of seaweeds annually. Another farm model can produce in 1 ha 55 tons of seabream or 92 tons of salmon, with 385 or 500 fresh weight of seaweed, respectively, without pollution. Preliminary calculations show a potential for high profitability with large integrated farms. Several freshwater integrated fish–vegetable farms and a couple of modern fish–algae–shellfish/abalone integrated mariculture farms exist today, and several additional farms are planned. Three major international R&D projects promise to soon expand the horizons of the technology further. Therefore, modern integrated systems in general, and seaweed-based systems in particular, are bound to play a major role in the sustainable expansion of world aquaculture.
A 50-day experiment was conducted to investigate the effectiveness of the bio-flocs technology for maintaining good water quality in over-wintering ponds for tilapia hybrid fingerlings (Oreochromis niloticus × Oreochromis aureus). To preserve adequate water temperatures in the ponds, they were covered with polyethylene sheets and the water exchange rate was minimized to increase pond water temperature. To avoid water quality deterioration, starch was added to the ponds to stimulate the formation of bio-flocs. Temperature in the covered ponds could easily be controlled and was 0.4–4.9 °C higher than the influent water. Adjusting the C/N ratio in the ponds by adding starch or increasing the amount of carbohydrates added through the feed limited the presence of inorganic nitrogen species when the C/N was about 20, even at high stocking densities of 20 kg/m3 at harvest. Fish survival levels were excellent, being 97 ± 6% for 100 g fish and 80 ± 4% for 50 g fish. Moreover, at harvest the condition of the fish was good in all ponds with a fish condition factor of 2.1–2.3. Overall, these findings can help to overcome over-wintering problems, particularly mass mortality of fish due to low temperatures in the ponds.
Glycinebetaine, a novel product from sugar beet (Beta vulgaris L. v. altissima), is purified from molasses during sugar processing through chromatographic separation, enrichment and crystallisation. Glycinebetaine is environmentally safe, non-toxic and water-soluble and is found in animal, microbe and plant cells. Most halophytes, when grown under stress, synthesise glycinebetaine in their chloroplasts and accumulate it as an osmoprotectant. Here we show that foliarly applied glycinebetaine offers a new possibility to stabilise crop production under field conditions: fruit yield of tomato plants (Lycopersicon esculentum Mill.) grown in saline soils or exposed to high temperatures in California increased up to 39% when glycinebetaine was applied during midflowering. Similarly, glycinebetaine treatment of tomato plants in a commercial vegetable producer's greenhouse in Southern Finland increased the yield and the number of tomato fruits. In a separate greenhouse experiment, we showed that glycinebetaine application increased the rate of net photosynthesis of adequately watered and salt stressed tomato plants.
We examined the influence of addition of common carp (Cyprinus carpio) and artificial feed in rohu (Labeo rohita) ponds. We analyzed the relationships among four datasets on different components of the pond food web (water quality, food availability, natural food intake, and fish growth and production) with the aim to examine the effects of the addition of common carp and/or artificial feed on the different components of the pond food web, and to analyze the nature and strength of the interactions between these components. We used redundancy analysis (RDA) to investigate these effects and interactions. We found that the addition of common carp increased bio-available N and P in the water column. Artificial feed addition increased N and P only in the presence of common carp. N and P increases were more pronounced in the presence of 0.5 than in the presence of 1 common carp m− 2. Plankton availability was strongly positively correlated with bio-available N and P. Phytoplankton availability correlated strongest with PO4–P, and zooplankton availability correlated strongest with PO4–P and DO. Natural food intake in rohu was positively correlated with plankton availability in the pond water and rohu growth was also positively correlated with natural food intake. Rohu preferred plankton over artificial feed, which acted as a fertilizer for rohu growth. Common carp preferred artificial feed over natural food and its growth was higher in the presence of artificial feed and negatively correlated with natural food availability.
Controlling the inorganic nitrogen by manipulating the carbon/nitrogen ratios is a potential control method for aquaculture systems. This approach seems to be a practical and inexpensive means of reducing the accumulation of inorganic nitrogen in the pond. Nitrogen control is induced by feeding bacteria with carbohydrates, and through the subsequent uptake of nitrogen from the water, by the synthesis of microbial proteins. The relationship among the addition of carbohydrates, the reduction of ammonium and the production of microbial proteins depends on the microbial conversion coefficient, the C/N ratio in the microbial biomass, and the carbon contents of the added material. The addition of carbonaceous substrate was found to reduce inorganic nitrogen in shrimp experimental tanks and in tilapia commercial-scale ponds. It was found in tilapia ponds that the produced microbial proteins are taken up by the fish. Thus, part of the feed protein is replaced and feeding costs are reduced. The addition of carbohydrates, or the equivalent reduction of proteins in the feed, can be quantitatively calculated and optimised, as shown here. Approximate parameters were used in this work. Additional research in this field should be directed at gathering the precise data needed for the exact planning of feed composition.
As the aquaculture industry intensively develops, its environmental impact increases. Discharges from aquaculture deteriorate the receiving environment and the need for fishmeal and fish oil for fish feed production increases. Rotating biological contactors, trickling filters, bead filters and fluidized sand biofilters are conventionally used in intensive aquaculture systems to remove nitrogen from culture water. Besides these conventional water treatment systems, there are other possible modi operandi to recycle aquaculture water and simultaneously produce fish feed. These double-purpose techniques are the periphyton treatment technique, which is applicable to extensive systems, and the proteinaceous bio-flocs technology, which can be used in extensive as well as in intensive systems. In addition to maintenance of good water quality, both techniques provide an inexpensive feed source and a higher efficiency of nutrient conversion of feed. The bio-flocs technology has the advantage over the other techniques that it is relatively inexpensive; this makes it an economically viable approach for sustainable aquaculture.
Luminescent vibrios, bacteria belonging to the species Vibrio harveyi and closely related species, are important pathogens in aquaculture that can affect almost all types of cultured animals. Due to large-scale use of antibiotics, many luminescent vibrios have acquired (multiple) resistance, which render antibiotic treatments ineffective. One of the alternative strategies that has recently been developed to control infections caused by antibiotic-resistant bacteria is the disruption of quorum sensing, bacterial cell-to-cell communication. The quorum sensing system of V. harveyi has been studied quite intensively in vitro. Recent studies have been directed towards understanding the impact of quorum sensing and quorum sensing disruption on the virulence of luminescent vibrios towards different host organisms in vivo. This mini-review aims at discussing the current knowledge of quorum sensing in luminescent vibrios in vivo. Subsequently, quorum quenching by halogenated furanones is discussed and finally, some directions for further research are presented.
In this study, we investigated the effect of poly β-hydroxybutyrate (PHB) on the culture performance of larvae of the giant freshwater prawn Macrobrachium rosenbergii and on the bacterial levels inside the larval gut. Instar II Artemia nauplii were cultured with or without PHB (5 g l-1) and/or a lipid emulsion rich in highly unsaturated fatty acids (HUFA) for 24 h. The effect of feeding PHB and/or HUFA-enriched Artemia nauplii on the performance of Macrobrachium larvae was investigated. Feeding larvae of the giant freshwater prawn with PHB-containing Artemia nauplii significantly increased survival and development of the larvae. Moreover, total bacterial counts and Vibrio spp. counts were found to be significantly lower in PHB-fed larvae when compared to control larvae, indicating that the PHB addition had a growth-inhibitory effect towards these potentially pathogenic microorganisms. Finally, a combination of PHB addition and lipid enrichment resulted in the best overall culture performance since it significantly improved larval survival as well as larval development. The optimal PHB concentration and formulation for bio-encapsulation into Artemia should be investigated further to increase the economical efficiency of Macrobrachium larval production.
Aquaculture effluents may contain a variety of constituents that could cause negative impacts when released into the environment. The constituents include dissolved or particulate organics, nutrients, and specific organic or inorganic compounds. Their impact on the environment depends on the total amount or concentration released and the assimilative capacity of the environment for the particular constituent. In this paper, the different types of constituents will be reviewed as they relate to a current trend in the aquaculture industry: intensification of production and recirculation systems.Although most water treatment methods used in intensive or recirculating aquaculture systems result in a relocation of nutrients and organic matter and not in an overall reduction in discharges, this relocation makes it possible to reduce potential environmental impacts by facilitating effluent treatment. For example, solids removal operations produce a stream with high concentration of solids (the sludge removed from the flow) that is also rich in nutrients and organic matter, while reducing the concentrations of these parameters in the culture water. The stream with a high concentration of solids could be treated prior to disposal using techniques appropriate for high strength wastes and sludge.The fate of constituents will be examined for a variety of water treatment operations. The impacts of a number of treatment methods on these constituents will be discussed from the standpoint of overall mass discharges and concentration of the constituents in the discharge flow.
The bacterial storage polymer poly-β-hydroxybutyrate (PHB) has the potential to be used as an alternative anti-infective strategy
for aquaculture rearing. In this research, the effects of (partially) replacing the feed of European sea bass juveniles with
PHB were investigated. During a 6-week trial period, the PHB showed the ability to act as an energy source for the fish. This
indicated that PHB was degraded and used during gastrointestinal passage. The gut pH decreased from 7.7 to 7.2 suggesting
that the presence of PHB in the gut led to the increased production of (short-chain fatty) acids. The diets supplemented with
2% and 5% PHB (w/w) induced a gain of the initial fish weight with a factor 2.4 and 2.7, respectively, relative to a factor 2.2 in the normal
feed treatment. Simultaneously, these treatments showed the highest bacterial range-weighted richness in the fish intestine.
Based on molecular analysis, higher dietary PHB levels induced larger changes in the bacterial community composition. From
our results, it seems that PHB can have a beneficial effect on fish growth performance and that the intestinal bacterial community
structure may be closely related to this phenomenon.
Disease problems have emerged as major constraints in aquaculture production. The prophylactic application of antibiotics is expensive and detrimental, i.e. selection of bacteria that are drug-resistant or more virulent and the prevalence of drug residues in reared animals. Probiotics, which compete with bacterial pathogens for nutrients and/or inhibit the growth of pathogens, could be a valid alternative to the prophylactic application of chemicals. A mixture of specific Bacillus strains was designed following a research programme on the ability of numerous Bacillus strains to inhibit a range of pathogenic Vibrio strains, to grow under conditions prevailing in shrimp hatcheries and to degrade waste products. These strains were then included in bioassays and challenge tests in order to confirm the lack of toxin production and pathogenicity to humans, target organisms and the environment. Here, we report on the performance of a commercially available mixture of Bacillus strains (SANOLIFE® MIC), using data from Asian and Latin-American hatcheries, with Penaeus monodon (Fabricius 1798) and Litopenaeus vannamei (Boone 1931). These results show that probiotics may be a suitable alternative to the prophylactic use of antibiotics. Obviously, minimizing the risk of vibriosis demands a multi-disciplinary approach, including good hygiene and sanitation measures to reduce the input of potential pathogens, as well as a suitable farm management.
In this study, we investigated the effect of poly β-hydroxybutyrate (PHB) on the culture performance of larvae of the giant freshwater prawn Macrobrachium rosenbergii and on the bacterial levels inside the larval gut. Instar II Artemia nauplii were cultured with or without PHB (5 g l− 1) and/or a lipid emulsion rich in highly unsaturated fatty acids (HUFA) for 24 h. The effect of feeding PHB and/or HUFA-enriched Artemia nauplii on the performance of Macrobrachium larvae was investigated. Feeding larvae of the giant freshwater prawn with PHB-containing Artemia nauplii significantly increased survival and development of the larvae. Moreover, total bacterial counts and Vibrio spp. counts were found to be significantly lower in PHB-fed larvae when compared to control larvae, indicating that the PHB addition had a growth-inhibitory effect towards these potentially pathogenic microorganisms. Finally, a combination of PHB addition and lipid enrichment resulted in the best overall culture performance since it significantly improved larval survival as well as larval development. The optimal PHB concentration and formulation for bio-encapsulation into Artemia should be investigated further to increase the economical efficiency of Macrobrachium larval production.
As a result of the stagnation of commercial fishery landings, aquaculture activities are expected to increase over the next decades to match the growing demand for marine protein. Overall, it is expected that the aquaculture sector could reduce some of the fishing pressure applied to wild stocks. However, this development is likely to be limited by the availability of key aquaculture inputs, specifically fishmeal and fish oil products (FMFOP). Aquaculture provided 60 % (fish meal) and 80 % (fish oil) of the world total consumption of these products in 2007. FMFOP are generally derived from small pelagic fish species, but can also be derived from other sources. Identifying the origin of FMFOP is crucial to understanding the effects of this new pressure on marine social-ecological systems. Two factors are of particular importance in the reduction sector transforming wild fish into fishmeal or fish oil: the two “conversion ratios” (i.e. the ratio between the quantity of wild fish harvested and the resulting quantity of FMFOP, and the ratio between the quantity of FMFOP and aquaculture production), and the type of raw material used by the reduction sector. Based on trade and production databases from FAO and the International Fishmeal and Fish oil Organisation (IFFO), this paper proposes an approach to identify the origin of FMFOP. It shows that whereas different countries use different pelagic resources to produce FMFOP, other countries use non-pelagic sources, and some countries use pelagic resources for human consumption.
This review deals with the main mechanisms and parameters affecting design and performance of trickling filters in aquaculture. Relationships between nitrification rates and easily accessible process parameters, like bulk phase concentration of TAN, O2, organic matter (COD), nitrite, temperature, HCO3−, pH and the hydraulic loading of the trickling filter, are discussed in relation to the design and operation of such filters. Trickling filter design procedures are presented and one of them, a model describing the nitrification performance of trickling filters by plug-flow characteristics, is discussed in greater detail. Finally, practical aspects in relation to filter design and operation are presented.
The three-dimensional pore structures in waste activated sludge floc were identified using the fluorescence in situ hybridization and confocal laser scanning microscope images. The interior of sludge floc was confirmed to have a multiscale structure, with pore cross-sectional area of as the transitional scale. Major advective flow would pass through the large pores, probed as a loosely packed, first level structuration. The chemical flocculation would enlarge the aspect ratio of large pores, while freezing and thawing reduced it. The second level structuration was comprised of fine pores with fractal boundaries, whose detailed structural information was extracted from the constructed floc model. After flocculation, the boundaries of fine pores would become more irregular, and freezing and thawing smoothed it. A sample calculation using the floc model demonstrated the intrafloc transport processes in flocs of multiscale structures.
Standardized evaluation and rating of biofilters for aquaculture should be assessed in the context of the economic efficiency of ecological services (waste assimilation, nutrient recycling, and internal food production) provided by earthen ponds, and the availability and cost of land, water, and electrical energy resources required to support particular classes of production systems. In photosynthetic suspended-growth systems, water quality control is achieved by a combination of natural and mechanical processes. Natural processes include photosynthesis of oxygen, algal nutrient uptake, coupled nitrification–denitrification, and organic matter oxidation; mechanical processes include aeration and water circulation. Ammonia is controlled by a combination of phytoplankton uptake, nitrification, and immobilization by bacteria. Unlike biofilters for recirculating aquaculture systems, unit processes are combined and are an integral part of the culture unit. The important design and operational considerations for photosynthetic suspended-growth systems include temperature effects, aeration and mixing, quantity and quality of loaded organic matter, and fish water quality tolerance limits. The principle advantages of photosynthetic suspended-growth systems are lower capital costs relative to other recirculating aquaculture systems and increased control over stock management relative to conventional static ponds. The main disadvantage is the relatively low degree of control over water quality and phytoplankton density, metabolism, and community composition relative to other recirculating aquaculture systems. Examples of photosynthetic suspended-growth systems include semi-intensive ponds, intensively aerated outdoor lined ponds, combined intensive–extensive ponds, partitioned aquaculture systems, greenwater tanks, greenwater tanks with solids removal, and greenwater recirculating aquaculture systems.
This paper analyses nutrient conversions, which are taking place in integrated intensive aquaculture systems. In these systems fish is cultured next to other organisms, which are converting otherwise discharged nutrients into valuable products. These conversions are analyzed based on nitrogen and phosphorous balances using a mass balance approach. The analytical concept of this review comprises a hypothetical system design with five modules: (1) the conversion of feed nutrients into fish biomass, the “Fish-Biomass-Converter”; (2) the separation of solid and dissolved fish waste/nutrients; the “Fish-Waste-Processor”; (3) the conversion of dissolved fish waste/nutrients, the “Phototrophic-herbivore-Converter”; (4 and 5) the conversion of solid fish waste, the “Bacterial-Waste-Converter”, or the “Detrivorous-Converter”. In the reviewed examples, fish culture alone retains 20–50% feed nitrogen (N) and 15–65% feed phosphorous (P). The combination of fish culture with phototrophic conversion increases nutrient retention of feed N by 15–50% and feed P by up to 53%. If in addition herbivore consumption is included, nutrient retention decreases by 60–85% feed N and 50–90% feed P. This is according to the general observation of nutrient losses from one trophic level to the next. The conversion of nutrients into bacteria and detrivorous worm biomass contributes only in smaller margins (e.g. 7% feed N and 6% feed P and 0.06% feed N 0.03 × 10−3% feed P, respectively). All integrated modules have their specific limitations, which are related to uptake kinetics, nutrient preference, unwanted conversion processes and abiotic factors.
Microbial flocs produced in suspended growth bioreactors could offer the shrimp industry a novel alternative feed. In this study, microbial flocs were produced in sequencing batch reactors (SBRs) using tilapia effluent and sugar as a growth media. It was determined that 1 kg of microbial floc could be produced per 1.49 kg of sucrose. These microbial flocs were tested as an ingredient for shrimp feed over a 35 day feeding trial. Two control diets (absent of microbial flocs) were compared against three dietary treatments (microbial floc inclusion). Control 1 and microbial floc diets (diets 1–3) were formulated to be equivalent for levels of crude protein, total fat, crude fiber, calcium, magnesium, phosphorus, potassium, and sodium. Controls 1 and 2 did not contain microbial flocs and differed slightly from each other in soybean oil, krill meal, and mineral/salt levels. For diet 1 (microbial floc 7.8%) and diet 2 (microbial floc 15.6%), soybean protein isolate on a protein basis was replaced with microbial flocs at a 7.8 and 15.6% inclusion level on a dry matter basis. For diet 3, fishmeal was replaced with microbial flocs at 7.8% and fish oil at 0.50% (microbial floc 7.8% + fish oil). Four juvenile Litopenaeus vannamei were stocked per tank and each dietary treatment was tested in 12 replicates over a 35 day feeding trial. No differences were observed between final survival rates (93 to 100%) between any of the dietary treatments. Growth (weight gain per week) for control 1, control 2, diet 1, diet 2, and diet 3 were respectively 1.09 ± 0.14, 0.88 ± 0.14, 1.64 ± 0.03, 1.61 ± 0.03, 1.63 ± 0.04 g/week. The total gain in weight for the three diets containing microbial floc of 8.07 to 8.18 g in five weeks with an initial weight of 0.44 ± 0.005 g is truly exceptional. Tukey's HSD (Honestly Significant Differences) test revealed that each of the three microbial floc diets significantly (P < 0.01) outperformed each control in terms of weight gain per week with no differences in survival.
Disease outbreaks—some of them caused by pathogenic bacteria—are considered to be one of the largest constraints to development of the aquaculture sector. So far, antibiotics and disinfectants have only had limited success in the prevention or cure of aquatic disease. Moreover, the frequent use of biocides, especially in subtherapeutic doses, is leading to the rapid development of resistance. Therefore, there is an urgent need to develop alternative ways to control infections caused by bacterial pathogens in aquaculture. Many of these pathogens are found to control virulence factor expression by a cell-to-cell communication system. Hence, disruption of bacterial quorum sensing has been proposed as a new anti-infective strategy and several techniques that could be used to disrupt quorum sensing have been investigated. These techniques comprise (1) the inhibition of signal molecule biosynthesis, (2) the application of quorum sensing antagonists (including natural occurring as well as synthetic halogenated furanones, antagonistic quorum sensing molecules and undefined exudates of higher plants and algae), (3) the chemical inactivation of quorum sensing signals by oxidised halogen antimicrobials, (4) signal molecule biodegradation by bacterial lactonases and by bacterial and eukaryotic acylases and (5) the application of quorum sensing agonists. The few reports that deal with disruption of quorum sensing of aquatic pathogens, together with the results obtained with human and plant pathogens, indicate that this new approach has potential in fighting infections in aquaculture. However, before this new strategy can be applied in aquaculture, the impact of quorum sensing disruption on the virulence of aquatic pathogens and the impact of the proposed quorum sensing disrupting techniques on the aquaculture system of interest should be studied in more depth.
The present research investigated the effect of carbohydrate (CH) source for maintaining a high C:N ratio, and tilapia driven bioturbation on pond ecology, production and economical performances in C/N controlled periphyton-based (C/N-CP) freshwater prawn ponds. Two carbohydrate sources (high-cost tapioca starch and low-cost maize flour) were compared in 40 m2 ponds stocked with 80 freshwater prawn (Macrobrachium rosenbergii) juveniles (individual weight 0.81 ± 0.03 g) and 20 finfish fingerlings (Nile tilapia, Oreochromis niloticus and Indian major carp rohu, Labeo rohita) in three different combinations: 100% tilapia, 50% tilapia + 50% rohu, and 100% rohu (individual weight 27.7 ± 0.6 g). The CH sources for increasing C:N ratio from 10 (as in feed) to 20 had no significant effect (P>0.05) on water quality parameters, abundance of natural food (plankton, periphyton and benthos) and production of prawn and finfish. However, different fish combination had significant effects on pond ecology. The highest P04-P (P0.05) by the different stocking combinations of finfish. The net yield and survival of finfish were significantly higher in 100% tilapia ponds and lower in 100% rohu ponds resulting in 58% higher combined net yield (both prawn and finfish) in the former treatment during a 120-d culture period. This treatment gave the best economic return in terms of benefit-cost ratio while maize flour was used as CH source. In conclusion, maize flour can be used as an alternative cheap on-farm CH source for maintaining a high C:N ratio and tilapia driven re-suspension in C/N-CP system improves culture environment, natural food utilization, production and economic return, further enhancing economic sustainability of C/N-CP freshwater prawn farming system.
In this study, microbial mats were designed and constructed using microbial isolates obtained from semi-intensive shrimp culture ponds. Three microbial mats (MA, MB, and MC) were constructed on low-density polyester according to their capacity to remove inorganic nitrogen. Shrimp were stocked at three densities using twelve-day-old post-larval Litopenaeus vannamei (PL12). The mat cultures exhibited higher oxidation of ammonia to nitrite and nitrate nitrogen when compared with controls at higher stocking densities without water exchange. The lowest ammonia concentration was observed at the end of the experiment, 1.55 mg/l, found in mat C. However, mat C also registered the highest NO3 level, at 5.98 mg/l; in contrast, MB registered 1.50 mg/l of NO2-N and the lowest nitrate conversion (2.64 mg/l NO3-N). Control cultures (without mats) exhibited an increased accumulation of ammonia and no significant increases were observed in nitrite or nitrate. Growth and survival was enhanced with mat B co-cultured with 1000 PL m−2, which registered an average of 85.2% survival, and a yield of 423.5 g m−2. These values were significantly higher (P < 0.05) than control units. Moreover, the microbial biomass in mat composite, ∑MA + MB + MC evidenced active grazing and uptake of mat components by the shrimp. These findings can be used to recycle the excess N from shrimp production in a continuous and self-sufficient growth of indigenous microorganisms in the polyester support, thus providing additional food and water suitable to reuse for intensive shrimp larval rearing at low cost, particularly in closed culture systems with minimal or not water exchange.
The expansion of the aquaculture production is restricted due to the pressure it causes on the environment by the discharge of waste products in the water bodies and by its dependence on fish oil and fishmeal. Aquaculture using bio-flocs technology (BFT) offers a solution to both problems. It combines the removal of nutrients from the water with the production of microbial biomass, which can in situ be used by the culture species as additional food source. Understanding the basics of bio-flocculation is essential for optimal practice. Cells in the flocs can profit from advective flow and as a result, exhibit faster substrate uptake than the planktonic cells. The latter mechanisms appear to be valid for low to moderate mixing intensities as those occurring in most aquaculture systems (0.1–10 W m− 3). Yet, other factors such as dissolved oxygen concentration, choice of organic carbon source and organic loading rate also influence the floc growth. These are all strongly interrelated. It is generally assumed that both ionic binding in accordance with the DLVO theory and Velcro-like molecular binding by means of cellular produced extracellular extensions are playing a role in the aggregation process. Other aggregation factors, such as changing the cell surface charge by extracellular polymers or quorum sensing are also at hand. Physicochemical measurements such as the level of protein, poly-β-hydroxybutyrate and fatty acids can be used to characterize microbial flocs. Molecular methods such as FISH, (real-time) PCR and DGGE allow detecting specific species, evaluating the maturity and stability of the cooperative microbial community and quantifying specific functional genes. Finally, from the practical point of view for aquaculture, it is of interest to have microbial bio-flocs that have a high added value and thus are rich in nutrients. In this respect, the strategy to have a predominance of bacteria which can easily be digested by the aquaculture animals or which contain energy rich storage products such as the poly-β-hydroxybutyrate, appears to be of particular interest.
A poly-beta-hydroxybutyrate (PHB)-accumulating enrichment culture was obtained using activated sludge from a polyphosphate-accumulating reactor as inoculum. PHB accumulated by the enrichment culture significantly enhanced the survival of Artemia nauplii, infected with the virulent pathogen Vibrio campbellii LMG 21363. A strain was isolated from the enrichment culture, based on its ability to accumulate PHB, and 16S rRNA gene sequencing of the isolate revealed 99% sequence similarity to Brachymonas denitrificans AS-P1. The isolate, named PHB2, showed good PHB-accumulating activity (up to 32% of the cell dry weight). PHB accumulated by isolate PHB2 was able to protect Artemia completely from the V. campbellii strain. Our data indicate that PHB-accumulating bacteria, such as B. denitrificans PHB2, could be used as an an effective and economically interesting alternative strategy to control infections in aquaculture.
The wide and frequent use of antibiotics in aquaculture has resulted in the development and spread of antibiotic resistance. Because of the health risks associated with the use of antibiotics in animal production, there is a growing awareness that antibiotics should be used with more care. This is reflected in the recent implementation of more strict regulations on the prophylactic use of antibiotics and the presence of antibiotic residues in aquaculture products. For a sustainable further development of the aquaculture industry, novel strategies to control bacterial infections are needed. This review evaluates several alternative biocontrol measures that have emerged recently. Most of these methods are still in research phase; few have been tested in real aquaculture settings. It is important to further develop different strategies that could be combined or used in rotation in order to maximise the chance of successfully protecting the animals and to prevent resistance development.
This paper employs a general equilibrium model to examine how the rise of aquaculture and changes in wild fish stocks are related for herbivorous fish species. Two influences, human population growth and technological improvement in aquaculture, are studied. Both of these factors raise aquaculture production, but human population growth reduces wild fish stocks, while technological progress in aquaculture raises wild stocks.
To study the potential biocontrol activity of bioflocs technology.
Glycerol-grown bioflocs were investigated for their antimicrobial and antipathogenic properties against the opportunistic pathogen Vibrio harveyi. The bioflocs did not produce growth-inhibitory substances. However, bioflocs and biofloc supernatants decreased quorum sensing-regulated bioluminescence of V. harveyi. This suggested that the bioflocs had biocontrol activity against this pathogen because quorum sensing regulates virulence of vibrios towards different hosts. Interestingly, the addition of live bioflocs significantly increased the survival of gnotobiotic brine shrimp (Artemia franciscana) larvae challenged to V. harveyi.
Bioflocs grown on glycerol as carbon source inhibit quorum sensing-regulated bioluminescence in V. harveyi and protect brine shrimp larvae from vibriosis.
The results presented in this study indicate that in addition to water quality control and in situ feed production, bioflocs technology could help in controlling bacterial infections within the aquaculture pond.
"Developments during the past two years confirm the trends already observed at the end of the 1990s: capture fisheries production is stagnating, aquaculture output is expanding and there are growing concerns with regard to the livelihoods of fishers and the sustainability of commercial catches and the aquatic ecosystems from which they are extracted. The State of World Fisheries and Aquaculture 2004 reports on several of these issues. "It is not only fishers and fish farmers who have these concerns; they are increasingly shared by civil society at large. Moreover, the importance of international trade in fish and fish products, combined with the trend for major fishing and trading companies to operate on a multinational basis, means that such issues are becoming global in nature affecting a growing number of countries, be they large fish producers or large consumers of fish. It is heartening to note that governments and other stakeholders have begun to collaborate with their neighbours and partners in trade in an effort to find shared solutions. "Concrete examples of positive outcomes of this globalization of concerns are the establishment of new regional fishery management organizations and the strengthening of existing ones. It is probable that ongoing discussions among intergovernmental organizations on topics such as trade in endangered aquatic species, the use of subsidies in the fishing industry, and labour standards in fisheries will also result in agreements of overall benefit to world society. "Given the nature and tone of the international discussion on fishery issues and the developments observed during recent years, I believe that fishers and fish farmers, in collaboration with governments and other stakeholders, will overcome the obstacles they face currently and will succeed in ensuring sustainable fisheries and continued supplies of food fish at least at their present levels."
The discovery of anaerobic ammonium oxidation (anammox) has greatly improved the understanding of the nitrogen cycle. Anammox provides great promise for the removal of nitrogen from wastewater, containing high concentration of ammonium. However, the presence of organic carbon is considered as unfavorable to this autotrophic process, i.e. anammox. Most of the real wastewaters contain both organic carbon and nitrogen. Under this circumstance, several processes have been established primarily for the complete removal of organic carbon. Subsequently, the wastewater containing no or low organic carbon and nitrogen is treated via a variety of nitrogen removal processes. The co-existence of anammox and denitrification could be useful for the simultaneous removal of nitrogen and organic carbon in a single system rather than a sequential chain of treatment. This review addresses the microbiology, strategies, consequences and the future research challenges in the co-existence of anammox and denitrification.
Effects of Bacillus subtilis E20 isolated from fermented soybean on immune parameters and the disease resistance of the white shrimp (Litopenaeus vannamei) after 98 days of B. subtilis E20 feeding were evaluated in this study. Shrimp fed B. subtilis E20-containing diets at concentrations of 10(6) (E206), 10(7) (E207), and 10(8) (E208)cfu kg(-1), respectively, had significantly increased survival rates of 13.3%, 16.7%, and 20%, compared to the control (fed no probiotic) after being challenged with Vibrio alginolyticus. There were no significant differences in the total hemocyte count, respiratory burst, or superoxide dismutase glutathione peroxidase among all treatments. Shrimp fed a higher concentration of the probiotic (E208) exhibited significant increases in phenoloxidase activity, phagocytic activity, and clearance efficiency compared to control shrimp. In addition, B. subtilis E20 showed a weaker inhibitory effect against the growth of Aeromona hydrophila with around a 0.3-cm inhibitory zone, but showed no inhibitory effects against other selected pathogens, such as white shrimp pathogens: V. alginolyticus and Vibrio vulnificus. These results suggest that the increased resistance of shrimp after B. subtilis E20 consumption occurs through immune modifications, such as increases in phenoloxidase activity, phagocytic activity, and clearance efficiency against V. alginolyticus.
The potential use of sequencing batch reactors (SBRs) as an alternative bio-flocs technology (BFT) approach in aquaculture was explored. One SBR was dosed with glycerol and one with acetate for the decrease of the nitrogen concentration in simulated aquaculture water by microbial assimilation. At an optimal C/N ratio between 10 and 15, the nitrogen removal efficiency reached up to 98% (=110 mg N L(-1) reactor day(-1)) for both SBRs. The estimated biomass productivity reached 0.62-0.94 g C L(-1)r eactor day(-1) for the glycerol SBR and 0.54-0.82 g C L(-1) reactor day(-1) for the acetate SBR. The floc protein content, indicating biomass quality, reached up to 57% if grown on glycerol. With acetate, it attained a value of 61%. The highest average poly-beta-hydroxybutyrate (PHB) content was 16% on a dry weight basis for the acetate biomass.
There is an urgent need in aquaculture to develop microbial control strategies, since disease outbreaks are recognized as important constraints to aquaculture production and trade and since the development of antibiotic resistance has become a matter of growing concern. One of the alternatives to antimicrobials in disease control could be the use of probiotic bacteria as microbial control agents. This review describes the state of the art of probiotic research in the culture of fish, crustaceans, mollusks, and live food, with an evaluation of the results obtained so far. A new definition of probiotics, also applicable to aquatic environments, is proposed, and a detailed description is given of their possible modes of action, i.e., production of compounds that are inhibitory toward pathogens, competition with harmful microorganisms for nutrients and energy, competition with deleterious species for adhesion sites, enhancement of the immune response of the animal, improvement of water quality, and interaction with phytoplankton. A rationale is proposed for the multistep and multidisciplinary process required for the development of effective and safe probiotics for commercial application in aquaculture. Finally, directions for further research are discussed.
Infections caused by antibiotic-resistant luminescent Vibrios can cause dramatic losses in aquaculture. In this study, the short-chain fatty acid beta-hydroxybutyrate and its polymer poly-beta-hydroxybutyrate were investigated as possible new biocontrol agents. beta-Hydroxybutyrate was shown to completely inhibit the growth of pathogenic Vibrio campbelli at 100 mM. Moreover, the addition of 100 mM of this fatty acid to the culture water of Artemia nauplii infected with the V. campbelli strain significantly increased the survival of the nauplii. As Artemia is a non-selective and particle filter feeder, we also investigated whether poly-beta-hydroxybutyrate particles could be used to protect Artemia from the pathogenic V. campbellii. The addition of 100 mg l(-1) poly-beta-hydroxybutyrate or more to the Artemia culture water offered a preventive and curative protection from the pathogen as a significantly enhanced survival was noticed. If added as a preventive treatment, a complete protection of infected nauplii (no significant mortality compared with uninfected nauplii) was observed at 1000 mg l(-1) poly-beta-hydroxybutyrate. Our data indicate that the use of poly-beta-hydroxybutyrate might constitute an ecologically and economically sustainable alternative strategy to fight infections in aquaculture.
Time-series changes in transcript abundance of nine genes encoding important immune proteins in haemocytes or hepatopancreas of Pacific white shrimp Litopenaeus vannamei fed daily in a 1-week feeding trial diets containing three levels (0%, 0.2% or 1%) of beta-1,3-glucan from Schizophyllum commune were quantified by real-time PCR. As a whole, the immune modulation elicited by beta-glucan is bimodal, one swift reaction of up- or down-regulation occurred within 24h and a delayed regulation was commenced as late as 3-7days. Haemocyanin, crustin, prophenoloxidase (proPO) and transglutaminase (TGase) did not respond to the glucan treatment. While penaeidin 3 (Litvan PEN3) was swiftly down-regulated (0-24h), lysozyme and cytosolic manganese superoxide dismutase (cMnSOD) were swiftly up-regulated (0-24h). In contrast, the two pattern recognition proteins (PRPs), beta-glucan binding protein-high density lipoprotein (BGBP-HDL) and lipopolysaccharide/beta-glucan binding protein (LGBP), showed a delayed up-regulation. Their expressions were not maximized until as late as 72h or 7days, respectively, which coincide with the initiation of reported immune enhancement (6-24days) of PO and SOD activity, phagocytosis and superoxide anion production in penaeid shrimp receiving glucan-containing diet. These immune responses could be the downstream effects of the two PRP gene up-regulation that predispose the shrimp to a state of high immune responsiveness. Increased dosage of beta-glucan from 2 to 10gkg(-1) diet did not affect the expressions of the genes, indicating the sufficiency of beta-glucan supplementation at 2gkg(-1) diet.
Poly-beta-hydroxybutyrate(PHB)increasesgrowthperformanceandintestinal bacterialrange-weightedrichnessinjuvenileEuropeanseabass,Dicentrarchuslabrax
- De Schryver
- P Sinha
- A K Baruah
- K Verstraete
- W Boon
- N De
- G Boeck
- P Bossier
De Schryver, P., Sinha, A.K., Baruah, K., Verstraete, W., Boon, N., De Boeck, G., Bossier, P., 2010.Poly-beta-hydroxybutyrate(PHB)increasesgrowthperformanceandintestinal bacterialrange-weightedrichnessinjuvenileEuropeanseabass,Dicentrarchuslabrax. Applied Microbiology and Biotechnology 86, 1535–1541
Understanding Fish Nutrition, Feeds and Feeding (Publica-tion 420–256) Virginia Cooperative Extension, Yorktown (Virginia). 4 pp The basics of bio-flocs technology: the added value for aquaculture
- S Craig
- L A Helfrich
Craig, S., Helfrich, L.A., 2002. Understanding Fish Nutrition, Feeds and Feeding (Publica-tion 420–256). Virginia Cooperative Extension, Yorktown (Virginia). 4 pp. De Schryver, P., Crab, R., Defoirdt, T., Boon, N., Verstraete, W., 2008. The basics of bio-flocs technology: the added value for aquaculture. Aquaculture 277, 125–137.
Understanding Fish Nutrition, Feeds and Feeding (Publication 420-256). Virginia Cooperative Extension
- S Craig
- L A Helfrich
Craig, S., Helfrich, L.A., 2002. Understanding Fish Nutrition, Feeds and Feeding (Publication 420-256). Virginia Cooperative Extension, Yorktown (Virginia). 4 pp.