Effects of photoperiod on some Biological parameters of Clarias gariepinus Juvenile

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Journal of Stress Physiology & Biochemistry, Vol. 8 No. 4 2012, pp. 47-54 ISSN 1997-0838
Original Text Copyright © 2012 by Solomon, Okomoda
ORIGINAL ARTICLE
Effect of photoperiod on some biological parameters of Clarias
gariepinus juvenile
Solomon S.G.* and V.T. Okomoda
Department of fisheries and Aquaculture, University of Agriculture Makurdi, Nigeria
Telephone No.: +2347037275891
*E-Mail: solagabriel@yahoo.co.uk
Received July 1, 2012
Photoperiod effect on Growth parameters and cannibalism of Clarias gariepinus have been well
documented in resent past, but little is known about the response of other biological parameters
such as, Condition factor, Shooters composition, Body colouration and Blood glucose of this
important tropical fish species to different photoperiods, therefore the present study was designed
to evaluate these responses of the African catfish to 24 hours of light (00D:24L), 24 hours of
darkness (24D: 00L) and 12 hour light / 12 hours darkness (12D: 12L). The six weeks experiment
observed significant differences (P<0.05) in weight gain of the fish reared at the different
photoperiods with the highest value of 92.20g+1.10 obtained in fishes reared under a photoperiod
of twenty-four hours of darkness (24D: 00L) compared to those reared under a photoperiod of
twelve hours of light and twelve hours of darkness (12D: 12L) which had 69.80g +2.50 and the least
weight gain of 59.50g+8.2 was obtained under a twenty four hours of light (00D: 24L) photoperiod.
Despite the stress induced by light which affected the weight gain of the fish, condition factor of
the fishes in the different photoperiods did not vary significantly (P>0.05) at the end of the
experiment and were Significantly lower than value obtained at the start of the experiment,
Shooters composition was highest in 00D:24L (41.5% i.e. 27 of 65) leading to high mortality
(13.33%) due to cannibalism compared to 12D: 12L (Shooters =15.27% i.e. 11 of 72, Mortality= 4%)
and 24D: 00L (Shooters=5.33% i.e. 4 of 75, Mortality= 0%) photoperiod. More so, 93.33% (70 of 75)
of fish in the dark phase (24D: 00L) exhibited Deep shiny black body colouration, while 6.67% (5 of
75) was observed of Normal fish colouration. However the fishes in the 00D: 24L photoperiod were
observed to be predominantly Lighter skin colouration, (80% i.e. 52 of 65= lighter colouration,
18.46% i.e. 12 of 65= Normal skin coloration and 1.53 i.e. 1 of 65= Deep black body colouration)
while 12D: 12L were of Normal skin colouration (100% Normal skin colouration), also blood glucose
was observed to increase as the light hours increased (P<0.05) with 24D: 00L photoperiod having
the highest blood glucose level of 5.7+0.5, while those in 12D: 12L had 4.4+0.3 and 24D: 00L had
the least value of 3.9+0.1. This study therefore establishes the fact that photoperiod may have no
effect on the condition factor of African catfish, while higher shooters composition is highlighted as
one of the causes of increased mortality and could be reduced to a large extent with reduced light
phase therefore enhancing higher survival, also the use of blood glucose as an indicator of stress in
fish was justified in the present study.
Key words: Condition factor, Shooters composition, Body coloration, Blood glucose.
JOURNAL OF STRESS PHYSIOLOGY & BIOCHEMISTRY Vol. 8 No. 4 2012

Effect of photoperiod...
ORIGINAL ARTICLE
Effect of photoperiod on some biological parameters of Clarias
gariepinus juvenile
Solomon S.G.* and V.T. Okomoda
Department of fisheries and Aquaculture, University of Agriculture Makurdi, Nigeria
Telephone No.: +2347037275891
*E-Mail: solagabriel@yahoo.co.uk
Received July 1, 2012
Photoperiod effect on Growth parameters and cannibalism of Clarias gariepinus have been well
documented in resent past, but little is known about the response of other biological parameters such
as, Condition factor, Shooters composition, Body colouration and Blood glucose of this important
tropical fish species to different photoperiods, therefore the present study was designed to evaluate
these responses of the African catfish to 24 hours of light (00D:24L), 24 hours of darkness (24D: 00L) and
12 hour light / 12 hours darkness (12D: 12L). The six weeks experiment observed significant differences
(P<0.05) in weight gain of the fish reared at the different photoperiods with the highest value of
92.20g+1.10 obtained in fishes reared under a photoperiod of twenty-four hours of darkness (24D: 00L)
compared to those reared under a photoperiod of twelve hours of light and twelve hours of darkness
(12D: 12L) which had 69.80g+2.50 and the least weight gain of 59.50g+8.2 was obtained under a twenty
four hours of light (00D: 24L) photoperiod. Despite the stress induced by light which affected the weight
gain of the fish, condition factor of the fishes in the different photoperiods did not vary significantly
(P>0.05) at the end of the experiment and were Significantly lower than value obtained at the start of
the experiment, Shooters composition was highest in 00D:24L (41.5% i.e. 27 of 65) leading to high
mortality (13.33%) due to cannibalism compared to 12D: 12L (Shooters =15.27% i.e. 11 of 72, Mortality=
4%) and 24D: 00L (Shooters=5.33% i.e. 4 of 75, Mortality= 0%) photoperiod. More so, 93.33% (70 of 75)
of fish in the dark phase (24D: 00L) exhibited Deep shiny black body colouration, while 6.67% (5 of 75)
was observed of Normal fish colouration. However the fishes in the 00D: 24L photoperiod were
observed to be predominantly Lighter skin colouration, (80% i.e. 52 of 65= lighter colouration, 18.46%
i.e. 12 of 65= Normal skin coloration and 1.53 i.e. 1 of 65= Deep black body colouration) while 12D: 12L
were of Normal skin colouration (100% Normal skin colouration), also blood glucose was observed to
increase as the light hours increased (P<0.05) with 24D: 00L photoperiod having the highest blood
glucose level of 5.7+0.5, while those in 12D: 12L had 4.4+0.3 and 24D: 00L had the least value of 3.9+0.1.
This study therefore establishes the fact that photoperiod may have no effect on the condition factor of
African catfish, while higher shooters composition is highlighted as one of the causes of increased
mortality and could be reduced to a large extent with reduced light phase therefore enhancing higher
survival, also the use of blood glucose as an indicator of stress in fish was justified in the present study.
Key words: Condition factor, Shooters composition, Body coloration, Blood glucose.
The effects of environmental variables like
temperature, pH, and salinity on the growth,
survival and physiological responses of fish have
been thoroughly investigated in many tropical
species. Temperature for instance plays an
unquestionable role in the growth of fish belonging
JOURNAL OF STRESS PHYSIOLOGY & BIOCHEMISTRY Vol. 8 No. 4 2012
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Solomon, Okomoda
to the ectothermic species (Person-Le et al.,2006),
Photoperiod also is one of the exogenous factors
that directly influences the growth of fish through
changes in endocrine functioning and hormone
secretion, i.e. melatonin and thyroxin (Porter, et
al.,1999). Growth in fishes however is a measure of
the relationship between the length / weight and
condition factor of the fish, however works on the
condition factor of fish exposed to different
photoperiod is scarce and result obtained from the
few literatures available are highly varied cutting
across different species and sizes of fish, hence the
effect of photoperiod as an environmental factor
was assessed on condition factor of the African
catfish in this present study.
Cannibalism has been a problem in cultured
fisheries for ages, as in other fishes, stocking
density of African catfish is considered the most
important factor affecting cannibalism and
aggression (Almaza´n Rueda, 2004). In African
catfish, however, the present of large numbers of
“shooters” may increase the mortality of fishes due
to cannibalism as they are twice the average size of
the population though of the same age, and can
easily predate the weaklings, therefore any method
that can reduce their number in the population will
be a better management practice for fisheries
development as it will reduce cannibalism as well as
reduce continuous disturbance of the culture
chamber through sorting a method popularly used
in the control of shooters.
Blood glucose levels have long been used as
indicators of stress in fish (Wedemeyer and
McLeay,1981). Yet, in many studies under stress,
blood glucose either remained unchanged or took a
longer duration of stress to show the change
(Pottinger et al., 2002). These differences has been
suggested to be related to the nature of the
stressor, duration of the stressor or inter-species
differences in glucose utilization and turnover
during stress, therefore, since Artificial photoperiod
regimes are alterations in the natural light/dark
cycles and any alteration or manipulation of
environmental parameters such as temperature or
light results in abrupt changes in the environment
which may cause stress thus compromising the
welfare and general well-being of the fish
(Wendelaar Bonga 1997), the present study was
therefore designed to assess the response of
African catfish juvenile to different photoperiod as
it affects it growth, condition factor, shooters
composition, body colouration, and blood glucose.
MATERIALS AND METHODS
Juvenile of Clarias gariepinus was obtained from
the Department of Fisheries and Aquaculture
research farm of the Federal University of
Agriculture Makurdi through induced breeding and
acclimatized for two weeks at the university fish
hatchery where the experiment was conducted.
The re-circulatory system where the fish were
maintained had an average flow rate of 4 L min-1
with water quality within desirable range for
growth of fresh water fish species (dissolved
Oxygen-7.5-11.5 mg/l; pH 7.1-8.5; water
temperature 25-30ºC). Twenty-five (25) C.
gariepinus fingerlings of mean weight of 9.02g+0.12
were selected at random and weighed by means of
a sensitive weighing balance. The groups of fish
were then placed in the nine rearing tanks
connected to the water circulatory system. The nine
tanks were assigned to three photoperiods namely
twenty-four hours of light (00D: 24L), twelve hours
of light twelve hours of darkness (12D: 12L) and
twenty-four hours of darkness (24D: 00L). The light
phase was achieved with the aid of an energy bulb
(60W) emitting 150 lux intensity of light measured
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Effect of photoperiod...
at the surface of water while the dark phase was by
completely covering the assigned rearing tank with
tarpaulin material to reduce light intensity to 5lux
measured at the surface of the water.
The fishes during the course of the experiment
were fed 5% of their body weight with 2mm
Coppens feed (8.2% Moisture, 9.5% Ash, 45%
Crude protein, 12% Ether extract, 1.5% Crude fiber).
The experiment lasted for 42 days.
Data collection
Individual body weights were taken at the start
and subsequently once biweekly till the end of the
experiment to measure growth increase. All fish
were blotted to remove excess liquid and weighed
using a sensitive weighing balance fish in the dark
phase were weighed in darken containers which
weight have been previously determined and
zeroed with the weighing balance this is to avoid
any form of hormonal interaction which can be
caused switch in photoperiod regime. Length was
measured at the start and end of the experiment
with a meter rule. Condition factor of fish was
determined sat the start and end of the experiment
by the formular.
CF = Wt x100
Length3
Shooter composition was determined by
estimating the percentage of fish that weighed
twice the mean weight of the fish in each
photoperiod and this was determined at the end of
the experiment.
Body colouration was determined by three
teams of previously trained observers composed
mainly of four women in each team. Colouration
was described as Lighter skin colouration, Normal
skin coloration and Deep shiny black body
colouration, It is however important to Note that
observers were predominantly women because of
the Notion that men are colour blind.
Blood glucose was determined using a blood
glucose kit obtained from Aboli Medical laboratory
Makurdi. Blood samples taken to determine this
was gotten from two fishes randomly selected from
each treatment, a drop of the blood sample was
placed on the strips connected to the Accu-chek
active kit model CE00HH and result was obtained in
situ.
Statistical Analysis of results was done with a
computer Programme Gen stat discovery edition.
RESULTS
Photoperiod effects were observed on most of
the parameters measured. Figure 1 shows the
growth of fish biweekly of exposure to the different
photoperiod. Fish exposed to 24D: 00L had the
highest maximum weight of 92.20g+3.10 at the end
of the experiment compared to 12D: 12L which had
69.80g+2.50 and 00D: 24L had the least weight gain
of 59.50g+8.2 (Table 1). Also it was observed that
the condition factor of the fish at the end of the
experiment were not significantly different across
the treatments and were reduced compared to the
value at the start, Shooters composition was highest
in 00D: 24L (41.5% i.e. 27 of 65) compared to 12D:
12L (15.27% i.e. 11 of 72) and 24D: 00L (5.33% i.e. 4
of 75) photoperiod. 93.33% (70 of 75) of fish in the
24D: 00L exhibited Deep black body colouration,
while 6.67% (5 of 75) was observed of Normal fish
colouration. Though the fish in the 00D: 24L
photoperiod were observed to be predominantly
Lighter skin colouration, (80% i.e. 52 of 65), 18.46%
(12 of 65) were of Normal skin coloration while 1.53
(1 of 65) were of Deep shiny black body colouration,
however fish in the 12D: 12L were of Normal skin
colouration (100% Normal skin colouration), also
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Solomon, Okomoda
blood glucose was observed to increase as the light
hours increased (P<0.05) with 24D: 00L photoperiod
having the highest blood glucose level of 5.7+0.5,
while those in 12D: 12L had 4.4+0.3 and 24D: 00L
had the least value of 3.9+0.1 (Table 2).
Table 1 Condition factor
Treatment Total length (cm) Mean
+ S.E.
Weight (g)
Mean +S.E.
N Mean condition factor
+S.E.
Before.
Control 10.17+0.245 9.02+0.59 75 0.872+0.029
Light 10.33+0.206 9.01+0.62 75 0.869+0.023
Dark 10.20+0.235 9.00+0.62 75 0.929+0.066
After
Control 18.59+0.93ab 69.80+2.5b72 0.818+0.022
Light 17.68+2.59c59.50+8.2c65 0.839+0.014
Dark 19.35+0.55a92.20+1.1a75 0.892+0.035
N-sample size; S.E.-standard error
Means in the same column with different superscripts differ significantly (P<0.05)
Means condition factor differ significantly before and after the experiment
Table 2: Blood glucose and shooters composition of fish at different photoperiod
PARAMETERS CONTROL LIGHT DARK
Blood glucose 4.4+0.3b5.7+0.5a3.9+0.1c
Shooters composition
No of shooters 11 27 4
No of fish at the end
of the experiment
72 65 75
Percentage shooters
composition
15.27 41.5 5.33
No of fish at the start
of the experiment
75 75 75
Percentage mortality
(%)
4 13.33 0
Figure 1: Mean weight of fishes per week reared at the different photoperiods (P<0.05).
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Effect of photoperiod...
Figure 2: Variation in body colouration of fish exposed to different photoperiod.
DISCUSSION
Results from the present study showed that
photoperiod affect growth of the African catfish
juvenile. Lower performance is the suggested cause
of higher growth in 24D: 00L and is related to the
innate behaviour of Africa catfish while increased
performance caused lowered growth as a result of
the stress by longer periods of light (Appelbaum
and Kamler, 2000) because more time is spent
searching for cover and display of aggression in
territorial behaviour (Appelbaum and McGeer,
1998). However it should be noted that,
photoperiod effects on growth in fish are clearly
species specific depending on the daily activity
rhythms (diurnal/nocturnal) and probably the light
sensitivity which has been shown to differ greatly
between species (Migaud et al., 2008) hence the
contradiction of the present study with studies on,
Tilapia spp (Abdel-Fattah and Mamdouh Kawanna
2004)
Condition factor of fingerlings reared at the
different photoperiod did not differ
significant(P>0.05), Luciano et al., 2009 observed
that condition factor of Odontesthes argentinensis
larvae reared at18L: 06D was similar to those
exposed to constant illumination (P>0.05) and was
higher (P<0.05) than larvae reared in the dark and
at 12L:12D, they however concluded that
Significantly reduced growth and condition factor of
fish larvae reared in the dark was due to reduced
feed consumption due to the lower probability of
encounter with their prey since the fish is
carnivorous in feeding, despite the carnivorous
nature of the African catfish the present or absent
of light may not be the determinant of feeding,
instead extended light stress this species and so
affect growth hence response of condition factor to
photoperiod may be species specific. The present
study also observed a decrease in condition factor
after the six weeks experimental period, this
reduction in the condition factor of the fish in the
different treatments may be due to reduced space,
and gonadal development as fishes at the end of
the experiment were advanced juveniles. Saliu,
(2002) stated that condition factor is not constant
for a species or population over time interval and
might be influenced by both biotic and abiotic
factors such as feeding regime and state of gonadal
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Solomon, Okomoda
development. However the insignificant result
gotten in this study with respect to condition factor
may be due to increased food intake despite stress
of fishes reared at artificial photoperiod of 00D: 24L
as the study observed 13.33% mortality in this
photoperiod with dead fishes missing many parts
indicating cannibalism. Therefore with regards to
photoperiod as an external environmental factor;
there is a possibility that Condition factor of Clarias
gariepinus is un-affected by photoperiod, hence
more research is needed to confirm this position.
With respect to body colouration, fish reared at
the different photoperiod exhibited camouflage
behaviour taking to the colour of the rearing
medium, deep black colouration was observed
predominant in 24D: 00L photoperiod possibly
because of the darken nature of the facility while
lighter body colouration was observed in the
completely illuminated medium. Though
Photoperiod has earlier been stated to affect body
pigmentation, (Biswas et al., 2002) literature on
changes in the pigmentation of fishes exposed to
different photoperiod are scares, and this may be
due to the fact that the colour change is not stable
and can be lost within few hours of exposure to a
different photoperiod, the observation of some fish
in the dark phase (24D: 00L) exhibiting 6.67% (5 of
75) of Normal fish colouration as against the Deep
black body colouration predominantly (93.33% i.e.
70 of 75) exhibited among the fish, as well as
18.46% (12 of 65) Normal skin coloration and 1.53
(1 of 65) Deep black body colouration as against the
predominantly Lighter skin colouration, (80% i.e. 52
of 65) observed in the 00D: 24L brings to mind
specific genetic difference which may slow down or
accelerate an organism reaction to environmental
factor such as photoperiod, However the
mechanism of operation leading to this obvious
changes in fish colouration is not well understood
hence, the need for more research.
As in other fishes, stocking density of African
catfish is considered the most important factor
affecting cannibalism and aggression (Almaza´n
Rueda, 2004). However in African catfish,
cannibalism is also affected by factors other than
stocking density such as photoperiod (Almaza´n
Rueda et al., 2004). Although many studies have
cling increased cannibalism to stress caused by
longer periods of light because more time is spent
searching for cover and display of aggression in
territorial behaviour (Appelbaum and McGeer,
1998). The present study has however
demonstrated that increased shooter composition
may have contributed immensely to the mortality
observed as it favored cannibalistic behaviour.
Studies on Blood glucose as indicators of stress
in fish are highly varied in terms of observations, in
many studies under stress, blood glucose either
remained unchanged or took a longer duration of
stress to show the change (Pottinger et al., 2002).
Srivastava and Sanjeev (2010) reported that
exposure of Clarias batrachus to artificial
photoperiod (24L: 0D and 0L: 24D) for a short
duration of 24 hour did not show any significant
change in blood glucose concentrations. In the
present study however blood glucose increased as
the number of light hours increases, fish exposed to
00D: 24L photoperiod had the highest blood
glucose level, while those in 24D: 00L had the least
(P<0.05),. The present study has therefore revealed
that with respect to photoperiod under increasing
light phase for a period of 6 week blood glucose
level increases in the African catfish fingerling.
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