CONSERVATION OF AN
ENDANGERED CARNIVOROUS FISH RITA RITA THROUGH
INDUCED BREEDING
*HAYAT S1,2, RAMZAN M2,
ZAFARULLAH M2, AHMAD I2, ALI Q1, *MALIK A1
1Institute of Molecular Biology and Biotechnology, The University of Lahore,
Lahore, Pakistan
2Fish
Biodiversity Hatchery Punjab Fisheries Department, Chashma, Mianwali, Pakistan
Corresponding
author E-mail: skndrhayat93@gmail.com , arifuaf@yahoo.com
(Received
10th February 2020; Accepted 2th April 2020)
Abstract:
In present study the Effects of different doses of ovaprim
on induced spawning activities of Rita
rita were observed with an aim to standardize the dose
of ovaprim for successful breeding. In the trial experiment,
the females of Rita rita were treated with ovaprim at the rate of 0.5, 0.8 and
1.0ml/kg body weight and males of Rita rita in all the cases were treated at
the rate of 0.4ml/kg. The doses of ovaprim at the rates of
0.5, 0.8, 1.0 ml/kg body weight resulted in 0%, 100% and 100% ovulation
respectively. In case of injection of ovaprim at the
rate of 0.8ml/kg, the fertilization rate was observed to be about 70% and hatching
rate was 58%, which occurred within 20-25 hours after fertilization at water
temperature of 270C-290C. In case of injection of ovaprim
at the rate of 1.0ml/kg, 18% fertilization rate and 5% hatching rate was
observed. The doses of
ovaprim at the rates of 0.8ml/kg and 0.4ml/kg body weight for female and male Rita rita respectively was found to be satisfactory for overall breeding performance and the commercially successful production
of this fish. Hatchlings
from over all experiment were reared up to fingerlings size to about 2 month
and were finally stocked into the Chashma lake.
Keywords: Rita rita, Induced breeding,
Chashma Barrage, Conservation
Introduction
Sustainable
utilization of fish play very important role in improving the living standard
of human population of the Pakistan. It has been observed that 184 native
freshwater fish species, including 37 catfish species from order siluriformes
are present in Pakistan. Rita rita is a food fish and distributed in
Afghanistan, Pakistan, India, Nepal, Bangladesh and Myanmar (Mirza, 2003). Fry of Rita rita
are both surface and column feeder, fingerlings are marginal and bottom feeder
while it’s adult are bottom-dwelling carnivore and feed on mollusca, small
fishes, crustaceans, and insects as well as on decomposing organic matter. Rita rita also feeds
on aquatic algae, insects, crustaceans and rotifers (Gupta, 2015; Shrestha, 1990). Among
the catfishes,
Rita rita is commercially important and a well esteem food fish due to
having good taste and affluent protein meat. Recently Rita rita has been
regarded as ornamental fish. Many authors from different countries have
documented it as indigenous ornamental fish (Jalbani et al., 2016; Rafique and
Khan, 2012). It is locally called as “Khagga”
in Pakistan. This fresh water specie found in streams, rivers, canals, ponds
and occurs mainly in shallow waters. Young fishes are greenish brown above and
on flank and brownish white on abdomen. It is extremely slimy when captured (Rahman,
1989). Pakistan is a
land of high potential as far as its water resources are concerned. Fish
supplies more than 70% of animal protein required by her population. Fish has
become not only the most dependable source of animal protein but also a good
means of employment. It is therefore, essential that every inch of water body
be properly utilized for fish production and new commercially important fishes
should explored and domesticated for large-scale seed production, which will
eventually cover the way for aqua culturists to grow more fish. It is important
to mention that culture fishery is the single best contributor to the total
production of fish in the country. The main barrier toward this venture is the
non-availability of required number of stock able sized seeds of the concerned
species on demand. Only a reliable induced breeding and fry rearing technique
can ensure a steady supply of quality fish seeds.
In spite of good taste and popularity,
the R. rita fetching high price in the market, is now in endangered condition.
Up to now the induced breeding techniques for only few commercially important
fish species of Pakistan have been established. Until now the fry of R. rita
can only be collected from the river systems where they breed naturally. The population
of carps is gradually decreasing due to destruction of nesting and hatching
sites and excessive hunting. Increasing toxicity due to fertilizers, pesticides
in agro-forest land, gradual decrease in water level due to drought also led to
reduction in its population size. Due to the change in ecology of breeding
grounds, obliteration of nesting and destruction of sites for
hatching
imposed
negative impact on the fish survival. Some of the basic biology of R. rita has
been studied (Amin
et al., 2008; Molla et al., 2008). One of the possible
explanatory measures that can be taken against the extinction of this fish is
to initiate a domestication and breeding programme where by mass production of
quality seeds can be ensured. In view of the above, the present experiment was
undertaken to develop induced breeding technique of the cat fish R. rita.
Materials and Methods
An experiment was conducted on the
induced breeding of Rita rita, during
end of July 2015 in circular breeding tanks at Fish Biodiversity Hatchery
Chashma Barrage, Mianwali, Pakistan.
Brood stock was collected from Chashma reservoir, District Mianwali about one
year prior to this experiment in the month of April 2014 and this brood stock
was reared in earthen pond. The stock was reared on supplementary feeding
having about 45% animal protein level in addition to the natural food in the
pond. All the collected stock was checked
for maturity at the time of collection. Most of the male stock was matured but
no female was found to be ready for spawning. Periodical examination of the
stock was carried out to check the spawning possibility. To determine
the suitability of female brood for spawning, firstly few eggs were drawn from
the posterior region of the ovary using a catheter. Then eggs were immersed in
a solution containing 70 % acetic acid and 30% alcohol. After about five
minutes nuclei position was examined by using microscope. The acentric or
peripheral location of nuclei indicates readiness of fish for spawning, while
the central location of nuclei indicates unsuitability of fish for breeding. In last week of July 2015, brood stock was checked and was
found to be ready for spawning.
The brood fish were collected by
reducing the water of the pond on the day of the breeding trial. Good and
healthy broods were selected for breeding. Identification of male and female
broods was done on the basis of some external features. The females could be easily
recognized by their swollen abdomen and round and swollen urogenital papillae.
On the other hand, the mature males were identified by their flat abdomens and
long protruded genital papillae. Sexually mature males and females weighing approximately
were selected for induced breeding. Selected broods were kept in circular
breeding tanks with continuous water flow for about 6 hours for conditioning
prior to injection of ovaprim. Male and female fish were kept in separate
circular breeding tanks and constant water flow was maintained to ensure proper
aeration. Twelve females were divided into three treatments and marked as T1,
T2 and T3 (Table. 1) having three females in each treatment. The
females under each treatment were kept separately in different tank. The weight
of selected female broods ranged from 1130g to 1300g whereas the weight of the
males varied from 800g to 1100g. The females under treatment T1, T2
and T3
were treated with ovaprim at the doses of 0.5, 0.8, and 1.0 ml/kg
body weight respectively. While all the male under the treatment T1,
T2 and T3 were treated with ovaprim at the doses of 0.4ml/kg
body weight respectively. Throughout the experiment the water temperature remained
in range of 270C-290C.
On the basis of the body of brood, the
required amount of ovaprim was injected intramuscularly to the fish on the
dorsal side above the lateral line. After injection of ovaprim the females were
periodically checked every hour after 12 hours post-treatment with inducing
agent by gently pressing their abdomen. The females upon ovulation were
immediately stripped and eggs from each fish were collected in separate
fertilization trays. A male fish was stripped to obtain milt by using external
pressure to the abdomen immediately. To affect and ensure fertilization the
sperm suspension was mixed with eggs by gently stirring with a feather and
water was added to the egg–sperm mixture to activate the sperms for fertilizing
the eggs. Fertilized eggs were washed several times with clean fresh water to
remove the excess milt, blood etc. The fertilized eggs were incubated in
circular breeding tanks where they were in constant motion.
Percent ovulation, fertilization and
hatching rates were recorded to observe the effectiveness of different ovaprim
doses using following formulas.
For calculating
percent fertilization 100 eggs were taken from each group and number of
fertilized and unfertilized eggs was counted by observing under a microscope.
The unfertilized eggs turned whitish and opaque few hours after incubation
while the fertilized eggs remained transparent and showed distinct evidence of
cell division of embryo when observed under microscope.
Results and Discussion
In order to standardize the ovaprim dose
for induced ovulation in female R. rita, three different doses of
ovaprim were used. Data representing the effects of ovaprim doses on ovulation
of female fish, the rates of fertilization and hatching of eggs are presented
in Table 2. The result shows marked difference in effectiveness among 3 doses
in inducing ovulation, fertilization and finally hatching. The doses of ovaprim
at the rates of 0.5, 0.8 and 1.0ml/kg body weight resulted in 0%, 100%, and 100%
ovulation respectively. The time interval between the injection of ovaprim and
ovulation varied between 18h and 24h of injection in all cases. The fish which
did not ovulate within this time did not do so even after a period of 48 hours
of ovaprim injection. Females treated with the ovaprim dose of 0.5ml/kg body
weight showed no ovulation at all. The ovaprim dose
of 0.5ml/kg weight was found to be very low to provoke ovulation (Amin et al., 2008; Rahman, 1989).
In case of ovaprim treatment at the rate
of 0.8ml/kg, the average total number of eggs ovulated by individual female was
estimated to be 14000/female. The fertilization rate was observed to be about
70%. Hatching rate was approximately 58%, which occurred within 20-25 hours
after fertilization. In term of
ovulation, fertilization and hatching rates, the dose of ovaprim at rate of 0.8ml/kg body weight showed the best performance. Thus
fertilization and hatching rates of the eggs obtained from females treated with
0.8ml /kg were highest by body weight. In case of ovaprim treatment at the rate
of 1.0ml/kg, 18% fertilization and 5% hatching rate was observed (Haylor
and Mollah, 1995). The fish treated
at
the rate of 1.0ml/kg body weight, even if
induced ovulation in 100% fish, but the fertilization rate and hatching rate of
eggs was unsatisfactory. This lead to the conclusion that very large numbers of
eggs obtained from the fish treated with relatively higher dose (1.0ml/kg body weight) were immature and highly saturated with
blood. It may be regarded as the case abortion rather than normal ovulation. It
resulted in very low rate of both the fertilization and the hatching (Molla et al., 2008), when the Rita rita was treated with PG. Low PG
dose failed to induce spawning and thus resulted in 0% ovulation, while higher
PG doses induced 100% ovulation in females but unexpected insufficient
fertilization and hatching rates (Jalbani et al., 2016; Rafique and Khan, 2012).
Table 1. Different
dosage of ovaprim practiced during experiment
|
Treatments |
Sex |
Ovaprim
Dose(ml/kg) |
Sex |
Ovaprim
Dose(ml/kg) |
|
1 |
Male |
0.4 |
Female |
0.5 |
|
2 |
Male |
0.4 |
Female |
0.8 |
|
3 |
Male |
0.4 |
Female |
1.0 |
Table 2. Rates of ovulation, rate of
fertilization and rate of hatching of eggs of endanger catfish R. rita belonging
to three different Treatment doses of ovaprim
|
Treatments |
Dose of ovaprim (mg/kg of body weight) |
Weight of females (g) |
% females ovulated |
Average fertilization rate (%) |
Average hatching rate (%) |
|
|
Individual |
Average |
|||||
|
T1 |
0.5 |
1240 |
1226 |
0 |
- |
- |
|
1203 |
||||||
|
1236 |
||||||
|
T2 |
0.8 |
1130 |
1228 |
100 |
74 |
59 |
|
1256 |
||||||
|
1298 |
||||||
|
T3 |
1.0 |
1170 |
1216 |
100 |
18 |
5 |
|
1209 |
||||||
|
1270 |
||||||
Conflict of interest
The authors declared the absence of any
conflict of interest.
References
Mirza, M. R. (2003).
"Checklist of freshwater fishes of Pakistan," Zoological Society of
Pakistan.
Rahman, A. A. (1989).
"Freshwater fishes of Bangladesh," Zoological society of Bangladesh.
Shrestha, T. (1990).
Rare fishes of Himalayan waters of Nepal. Journal
of Fish Biology 37, 213-216.