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Vol. 20, Supplement 2, 2020 pp. 331-335 e-ISSN:2581-6063 (online), ISSN:0972-5210
A STUDY ABOUT SOME BIOLOGICAL ASPECTS OF INVASIVE MOLLY FISH
“POECILIA LATIPINNA” (LESUEUR, 1821) IN SOUTHERN IRAQ
Mohammed Enad Ghazwan
Iraq Natural History Museum & Research Center, University of Baghdad, Iraq
muhammadinad@yahoo.com
Abstract
This study attempts to highlight some aspects and vital traits of the invasive Molly fish “Poecilia latipinna” in Southern Iraq. These vital
traits include: some behavior traits in captivity and nutrition pattern; some phenotypic traits, as the relationship of Total length to weight,
sexual maturity, and sex; and especially some of the traits that characterize this particular type such as the shape of some body bones. This
species of fish was registered for the first time in Iraq in 2006 as an exotic fish in the Iraqi aquatic environment, specifically in waters
southern of Iraq.
Keywords : livebearer fish, exotic fish, ornamental fish, dorsal sailfin, Iraqi Marshes.
Introduction
Molly fish (Poecilia latipinna) is classified as a fish
belonging to the Cyprinodontiformes, and the livebearer
family of the Poecilidae. It is native to the whole area
between North America and Mexico. It lives in fresh and
brackish water, but prefers the latter over the former. It is
widespread almost all over the world because it is considered
an ornamental fish with high economic importance due to its
easy reproduction. Poecilia sphenops are the most common
species in the world, and there are many hybrids that have
descended and mixed amongst themselves from the free or
wild species such as P. latipinna, P. mexicana, P. sphenops
velifera as confirmed by (USGS NAS, 2014). The species
was first named as Mollienesia latipinna by the scientist
Lesueur in the year 1821, and was called the molly fish in
relation to the Molezenia genus as was defined (Lesueur,
1821); however, these fish were reclassified by the scientists
Rosen and Bailey, as they published for the first time a
systematic study of the livebearer family Poeciliidae, in order
to correct the genus from the Molezenia to the Pusilia. P.
latipinna is characterized by a different body than the first
species P. sphenops; the different colors and shape of the
dorsal fins in males resemble a sail, hence why it is known in
some studies as Sailfin molly. It was registered for the first
time as small fish gatherings in Europe, specifically in
Greece in 2016, as indicated by (Koutsikos, 2017). The
pollination is internal and hatch larvae of these fish inside the
mother's body and then goes out in a similar way to the birth
process, and that is why it was called a livebearer fish, as
explained by (Brian, 2010). It was registered for the first time
in Iraq in East of Hor Al-Hammar region in southern Iraq
(Hussain et al., 2009), and it was also seen in areas extending
from Shatt al-Arab and Abu Al-Khaseeb to Qurna. It is
possible it reached these natural areas in Iraq due to a flood
or an error in one of the ornamental fish farms, which led to
its escape into the Iraqi natural waters. It had an economic
importance for Iraqi fish farmers, since they were exporting it
as ornamental fish to Jordan and Syria (Brian, 2010).
This type of fish does not prefer deep water due to the
fact that it is a fish originally from waters of semi-coastal
areas with relatively shallow depths. It likes water with pH
(7.5- 8.2) and temperature (18-24C), as mentioned by (Riehl
and Baensch, 1996). The total length of Molly fish reaches
7.5 cm for adult fish, while its total length in the internal
waters of Iraq is 15 cm for adult females and 10-12 cm for
adult males as explained by (Brian, 2010). These fish feed on
worms, crustaceans and small-sized aquatic insects and some
aquatic plants; they are considered to be very fond of eating
green algae and lichens in waters as indicated by
(Welcomme, 1988) and (Riehl and Baensch, 1996). In
normal environmental conditions, it gives birth to about 20-
120 larvae after a 28-32-day pregnancy period. The number
may increase or decrease in indoor ponds used for raising
these fish in ornamental fish farms or regular glass Tanks,
and this is related to the age, general health status, and
nutrition with the ideal temperature for the breeding of these
fish.
Materials and Methods
A sample consisting of 50 molly fish (P. latipinna) was
collected from Al-Qurna area in Basra Governorate, southern
Iraq. The males were isolated from females in 100-liter
plastic tanks—each separately, to perform some biometrics
on the collected sample.
In this sample of males, the fish were stained to
highlight the shape of their body bones, according to the two
methods of (Potthoff, 1984) and (Taylor and Dyke, 1985).
The substances used in preparation for staining were:
1. Formaldehyde 10%
2. Ethanol (30%, 70%, 95%)
3. Hydrogen peroxide 15% + 0.1 Potassium hydroxide 85%
4. Acetic acid 30% + Ethanol 70% + Alcian blue stain
5. Sodium perborate (borax) 30%
6. Sodium perborate 30% + Trypsin enzyme
7. Potassium hydroxide 40% + Glycerine 60%
8. Potassium hydroxide 40% + Glycerine 60%
The Process:
1. If the fish are not preserved, they will be preserved in a
formalin solution with a concentration of 10% for five
days, after which the samples are washed with running
332
water and are kept for two days in pure water to get rid
of the effects of formalin; then they are washed a second
time and stored in ethanol alcohol at a concentration of
30% for a period of 2-5 days, depending on the size of
the fish—if they are 15 cm or longer, they are kept for
two days. Finally, they are kept in ethanol alcohol at a
concentration of 70% for another two days, depending
on the size of the samples.
2. Removing the internal organs of fish.
3. The fish samples are then kept in ethanol alcohol at a
concentration of 95% for another two days, and as for
fish that are more than 15 cm in length, they are kept for
a week.
4. The samples are placed in a solution consisting of 30%
acetic acid + 70% ethanol alcohol + a few grams of
Alcian blue stain so that the solution color is dark blue.
The samples are left for one day if their length is less
than 8 cm, and a day and a half if their length ranges
between 8 to10 cm.
5. Samples are placed in a saturated borax solution for one
day, if their length is longer than 10 cm, and the solution
is changed whenever it acquires a blue color.
6. Samples are placed in a solution consisting of 15%
hydrogen peroxide + 85% potassium hydroxide for no
more than an hour, until the bleaching process is
complete.
7. Samples are placed back in the saturated borax solution
plus trypsin enzyme, with the solution being changed
when it turns blue. It is better to change the solution
every 7 days until the ratio of clarity in the samples is
more than 60%, when the spine can be observed with a
blue color, and taking into account putting the samples
in this solution with light to accelerate the staining
process.
8. The samples are placed in a solution consisting of 1%
potassium hydroxide with an addition of an alizarin red
stain, so that the solution’s color is a very dark pink, and
keeping them for no more than 1-3 days until the bones
appear to be pink.
9. The samples are placed again in saturated borax and
trypsin solution as in step 7 and are left for another
week.
10. The samples are placed in a solution consisting of 70%
potassium hydroxide + 30% glycerine) for a period
ranging from two to seven days, then another solution of
(40% potassium hydroxide + 60% glycerine for another
two to seven days—the duration follows the size and
length of the fish samples.
Results and Discussion
The number of females collected for this sample was
15, while the total number of males for this sample was 35.
The females were all adults and sexually mature, while the
number of sexually mature males from the total sample
number was 11 adult males, and the number of sexually
immature males was 23 of the total number of males of this
sample. Figure (1) shows the male and female ratio of molly
fish collected in this study, and the female ratio exceeded the
male ratio in terms of the total number of fish in this sample.
Fig. 1 : Males to females ratio in the fish sample of the study.
As for Figure (2), it shows the ratio of sexual maturity
between males and females of the P. latipinna fish in this
study, and we notice that the number of sexually mature
males exceed the females which most of them were not
sexually mature in the fish sample collected for this study.
Fig. 2 : The ratio of sexual maturity between males and
females in the fish sample of the study.
To study the relationship between the total length and
weight of the collected fish sample, we notice in Table (1)
the following analysis of variance: significant differences are
found between males and females length (male superiority),
and significant differences also between the length of mature
and immature samples (the superiority goes to the mature
samples), As for weight, no significant differences were
observed between the samples, whether in terms of sex or
sexual maturity. As for the analysis between sex and sexual
maturity, no results were found due to the absence of
completely sexually immature males. This is compatible with
(Divya, 2018) in terms of the total length of sexually mature
fish. He explained that the total length ranges between (5-10)
for sexually mature fish raised in ponds outside their real
environment. He emphasizes in his study the approximate
total length in the sample of this study, which amounted to
(5.2) cm for the total sample of both males and females.
A study about some biological aspects of invasive molly fish “Poecilia latipinna” (Lesueur, 1821) in southern Iraq
333
Table 1 : The relationship between total length and weight of fish in this study.
Source Dependent Variable Type III Sum of Squares df Mean Square F Sig.
Total_Length 16.036
a
2 8.018 45.353 .000
Corrected Model Weight .115
b
2 .058 .823 .445
Total_Length 1389.969 1 1389.969 7862.063 .000
Intercept Weight 748.669 1 748.669 10696.554 .000
Total_Length 3.772 1 3.772 21.333 .000
Sex Weight .027 1 .027 .388 .536
Total_Length 2.254 1 2.254 12.747 .001
Maturity Weight .016 1 .016 .230 .634
Total_Length .000 0 . . .
Sex * Maturity Weight .000 0 . . .
Total_Length 8.309 47 .177
Error Weight 3.290 47 .070
Total_Length 1417.210 50
Total Weight 784.320 50
Total_Length 24.346 49
Corrected Total Weight 3.405 49
a. R Squared = .659 (Adjusted R Squared = .644)
b. R Squared = .034 (Adjusted R Squared = -.007)
In figures (3) and (4), the linear relationship between
total length and gender of the study fish sample, and the
linear relationship between total length and sexual maturity,
shows that no significant differences were found between
these relationships for the fish sample collected in this study.
The results here are similar to those of (Ahmed, 2012), as
there was no significant correlation between the relationship
of the total length of fish and the sex of those fish. Here, the
relationship of the total length with weight and sexual
maturity that are affected seasonally in fish, especially the
maturity of the genital organs in each of the males and
females, which are clear when studying the differences
between the weights of gonads in different seasons of the
year, according to the type and temperatures in the season in
which the samples are collected, as it explained by (Le Cren,
1951). It was pointed out that an increase in the size and
weight of gonads in both sexes in general, and an increase in
the size of ovaries in females in particular, was for the
purpose of increasing the accommodation of the largest
number of new embryos.
Fig. 3 : The linear relationship between the total length and
sex of the fish in the study.
Fig. 4 : The relationship between total length and sexual
maturity of the fish sample in the study.
Mohammed Enad Ghazwan
334
Table (3) shows the presence of a significant medium-
strong positive correlation between the total fish length and
weight with a correlation factor of R = 0.397. This
relationship is close to what (Hossain, 2010) came up with
when studying the relationship between different lengths and
weight of four species of fish that belong to Cyprinidae. It
demonstrates the positive direct relationship between the
total length of fish and the increase in body weight rates.
Table 3 : Shows the relationship between total fish length and weight of fish sample.
Total_Length Weight
Pearson Correlation 1
.397
**
Sig. (2-tailed) .004
Total_Length
N 50
50
Pearson Correlation .397
**
1
Sig. (2-tailed) .004
Weight
N 50
50
**. Correlation is significant at the 0.01 level (2-tailed).
As for the study of the body shape and the shape of the
molly fish skeleton in this study sample, a complete bone
staining process was performed according to the two methods
(Potthoff, 1984) and (Taylor and Dyke, 1985) for
pigmentation of small vertebrates. Two different modes of
lighting intensities were used. We observe from Figure (5) an
image of a male adult molly (P. latipinna), which was
photographed with spotlight only from the front, while the
details of the skeleton differed and the percentage of clarity
increased when the light from the front and back was shed on
a transparent board as in Figure (6), which gave more clarity
on the shape of the bones and their subtle details.
Fig. 5 : Shows adult molly (P. latipinna) with only front
lighting.
Fig. 6 : Shows the adult molly (P. latipinna) with back and
front bright lightening.
We notice from Figures (5) and (6) that the P.
latipinna’s body is oblong and the head is dorsally flattened,
with a small, upturned mouth suited for surface feeding. The
caudal peduncle is approximately as deep as the body and the
caudal fin is large and round. The dorsal fin is greatly
enlarged in mature males; the fin opens like a sail, and that is
why it is known as Sailfin Molly (Dawes, 1995). The mouth
of these fish contains many rows of very small teeth. The
males are distinguished by their gonopodium penis, which is
in fact a modified anal fin into a male reproductive organ that
distinguishes the fish of this family in general, as indicated
by (Robins, 2014). The males also have a skeleton that is
different in bone shape than the skeleton of females—males
have a wider body and the front of the head bones are more
tapered than the female. Moreover, the distribution of the
bones of the fins is completely different from the female fins.
These characteristics are associated with the sex of the
species studied here, and for the whole family of livebearer
fish. The chromosome number for this species has been
registered 48/24 (Froese and Pauly, 2014).
When raising the fish sample in captivity, it was
observed that they do not prefer common industrial foods
used to feed ornamental fish, whether local or foreign, but
rather prefer algae and lichens formed on the walls of the
ponds due to the stillness of the water and the intensity of
illumination from the sunlight shed on the ponds, and they
feed on it is voraciously. They also consumed and devoured
pieces of steam boiled chard; however, it was observed that
they can adapt to the available industrial food provided in the
captive. They prefer food with live plant origin, since P.
latipinna fish are mainly vegetarians, feeding voraciously on
algae, lichens and Periphyton (including natural components
of Periphyton, such as diatoms and detritus), as indicated by
Al-Kahem et al., 2007; Scharnweber et al., 2011; Barbiano et
al., 2014; Jaffe, 2014; Robins, 2014).
The water measurements studied in this experiment
were close to the water measurements mentioned by (Robins,
2014) in their real habitat in America, which shows the
suitability of the Iraqi aquatic environment for this species
and the speed of its adaptation to the new water, as shown in
Table (4) which illustrates the water measurements from The
gathering area in Al-Qurna, from Basra Governorate, and the
water of the breeding ponds at the place of study in Baghdad.
Table 4 : The studied water measurements
Water
Measurements Temperature pH KH GH NH3
NH4 TDS
Basra 26 C 8.2 143.2 PPM 451 PPM 0.25 ML / L 417 PPM.
Baghdad 25C 7.9 143.2 PPM 451 PPM 0. MG / L 406 PPM
A study about some biological aspects of invasive molly fish “Poecilia latipinna” (Lesueur, 1821) in southern Iraq
335
Females of P. latipinna fish are quick to abort their
fetuses when exposed to inappropriate environmental
conditions or physical and psychological stress on these
females. This trait is found in the species of P. latipinna, P.
mexicana, P. sphenops velifera without the rest of the species
that belong to the livebearer family of Poecilidae. This is
what happened when females were transported for a long
distance from Basra Governorate to Baghdad Governorate,
and no new births have been obtained when the fish that are
raised in captivity under different conditions from their real
environment in southern Iraq. This stress may cause
dysfunction in the endocrine glands of females, especially
one that could lead to an imbalance in the physiological
functions that are led by these glands, such as the ovaries and
their effect on the miscarriage of fetuses, which is illustrated
by (Gray, 2003), when there is an imbalance in the endocrine
function, gonads for female livebearer mosquitofish
(Gambusia affinis) will be affected.
Conclusion
In this study, we were able to partly identify some of
the vital traits of the invasive Molly fish (P. latipinna) in
southern Iraq. These traits are related to some phenotypic
characteristics, especially the shape of the skeleton of the
males in these fish by using the method of staining the bones
of small vertebrates. We were also able to identify the food
preferred by these fish when they are raised in captivity
ponds, isolated from their real environment. Moreover, we
learned about some different behaviors of these fish, in
addition to studying some linear relationships between some
vital traits that were positively related with each other, such
as the relationship of total height, sex, weight, and sexual
maturity of these fish. We recommend conducting some
analyses to find out the chromosome number of the invasive
species (P. latipinna) in southern Iraq in particular, and learn
whether there is a possibility that new hybrids kinds like this
could manifest in the Iraqi waters.
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Mohammed Enad Ghazwan
