Incubator Eggs Hatching

Incubator Eggs Hatching

INNOVATION ON THE HATCHING TECHNIQUE IN FLOW THROUGH SYSTEM OF ASIAN CATFISH CLARIAS BATRACHUS

P.P.Shelke and R.L.Kale

 

ABSTRACT

 

Asian catfish, Clarias batrachus is popularly known as magur.  It is one of the promising varieties of catfish found all over the country.  In spite of its high market price, demand of this species is considerable due to its protein rich flavour, presence of single central bone and medicinal value. Clarias batrachus attains maturity at the age of one year.  Magur is usually brad during June to August in Vidarbha region by applying hypophysation technique.  The recorded fecundity of fish Clarias batrachus is 50000 to 60000 eggs per Kg body weight of fish, which is too low as compared to Indian major carps.  The magur does not tolerate the rapid decrease in water temperature (as much as 2 o C /Hr).  It dies when subjected to constant temperature below 18 o C for period, longer than 1 month. 

 

The present work deals with the effect of light in the flow through system to increase the water temperature in hatchery phase of Clarias batrachus as compared to existing hatchery technology.  In Vidarbha region during the monsoon the average minimum temperature is found to be 16 o C which may decline up to 6 o C in extreme condition.  But the ideal water temperature required for the rearing of magur larvae is 22 o C to 30 o C.  In the existing flow through system the temperature monitoring system has not been used which seems to be necessary to increase the rate of survival of magur larvae. The magur being an air breathing fish could be cultured in shallow water bodies, the Vidarbha region, being drought prone can be well suited for its farming.  As the seed production technology for this species has not been standardized for the Vidarbha region, hence the present work is carried out to see the efficacy of innovative technique for survival of hatched larvae. 

 

Introduction:

 

The natural range of distribution of magur fish is Ceylon, India, Pakistan, Bangladesh, Burma, Malaysia, Thailand, Indo China, Philippines, Hong Kong and South China.  Clarias batrachus is well adapted to adverse an ecological condition that prevails in derelict water bodies which are generally shallow.  These waters are characterized by low dissolved oxygen and high carbon dioxide, methane and ammonia and are generally not suitable for survival of fishes other than air breathers.  By virtue of accessory respiratory organs these fishes are able to strive in this adverse situation.

 

Magur fish exhibits sexual dimorphism and differentiating secondary sexual characters are shape of muscular papilla at vent region.  Males have elongated papilla, while females with round button shaped papilla.  The fecundity of this species is very low, though the maximum fecundity recorded was 37720; fishes with a fecundity range of 15000 to 20000 are common.  The breeding period falls during June to August. 

 

The magur fish can be breed by inducing hormones @ 0.8 ml/Kg body weight to female.  The latency period between injection and stripping of female is 16 hours at 28 to 30 degree C.  The male fishes are held separately in a tank or container before artificial fertilization. 

 

Artificial Fertilization:

Before the female are stripped male fish with gravid testis are to be sacrificed, and testes are taken out and macerated in normal saline ( 0.9% NaCl).  The spermatozoa become inactive in this medium and this extract can be maintained for few hours in refrigerator.  After 16 hours of latency period female fish is stripped and ova are collected in to dry enamel tray.  Before fertilization milt (spermatozoa) extract medium is activated by addition of fresh water.  Sperms become active and motility of sperms can be confirmed in microscope.  Sperm preparation thus obtained will be sufficient to fertilize the ova stripped from 2 females.  Sperm extract is sprinkled over the ova and gamets are mixed gently with bird feathers and allowed to 2 to 3 minutes for fertilization.  After repeated washing with fresh water fertilized eggs are transferred to hatching trays for incubation.  The average fertilization rate of 65% was observed  in CIFA model in Vidarbha region. 

 

A) CIFA Model of Flow Through System :  This is a simple device comprising a stand on which are placed a row of plastic tubs ( 12 cm dia, 6 cm high).  Water supplied from the overhead tank through a common pipe to all the tubs with individual control tabs.  Each tub is provided with an outlet at a height of 4 cm and connected to a common conduit to drain off water. In this model of  flow through system the temperature monitoring system has not been used which seems to be necessary to increase the rate of survivality of magur larvae for the Vidarbha region.

                    

 

              

B) Innovative Model of Flow Through System :   

This is a modification In the CIFA flow through system by adding temperature monitoring system which is necessary to increase the rate of survivality of magur larvae.  This innovative model device comprises a stand on which are placed a row of plastic tubs ( 12 cm dia, 6 cm high).  Water supplied from the overhead tank through a common pipe to all the tubs with individual control tabs.  Each tub is provided with an outlet at a height of 4 cm and connected to a common conduit to drain off water.  Lights are fixed over each tub for maintaining the temperature in the tubs during incubation.  The wattage of bulbs is selected depending on the need of raise in temperature.  Normally 100 Watt bulb is sufficient to maneuver the temperatures in Vidarbha Region where, during the monsoon the average minimum temperature is found to be 16 o C which may decline up to 6 o C in extreme condition.  But the ideal water temperature required for the rearing of magur larvae is 22 o C to 30 o C.

 

 

                     Bulb1      Bulb2        Bulb3       Bulb4       Bulb5

             

Fig2:  Plastic Tub  Flow Through System for incubating eggs (Innovative model)

 

 

Materials and Methods:

 

For getting the fertilized eggs the following procedure has been adopted.  Initially selected the female brood fish based on the visual observations of bulged belly and oozing ova on little pressure.  The selected females were put in larger plastic trough.  Males were selected by ensuring the age and well developed vascularized papilla since they do not spermite on applying pressure at vent region like carp.  Then females were injected by synthetic gonadoprophins hormones i.e. ovaprim  @ 0.8 ml per kg body weight.  The latency period between injection and stripping of female was 16 hours at 28 to 30 Degree C (water temperature.).  The male fishes were held separately in a large plastic tank before artificial fertilization. 

 

 

 

Fertilization:

 

            Before stripping the females, male fish with gravid testes was to be sacrificed and testes were taken out and macerated in normal saline (0.9% NaCl).  The spermatozoa become inactive in this medium and this extract can be maintained for few hours in the refrigerator.  After 16 hours of latency period female fish was stripped and oiva were collected in to dry enamel tray.  Then the milt suspension were added on the eggs with the help of dropper, then the ova and gametes were mixed gently with bird feathers and allowed to 2-3 minutes for fertilization.  After repeated washing with fresh water fertilized eggs were transferred in to incubation troughs.

 

Incubation:

            After transferring the fertilized eggs to the flow through incubating system, a feeble flow of water was provided to maintain good water quality.  The water temperature between 27-30 degree C was maintained for development and hatching.

Both the models were simultaneously operated to breed the Clarias batrachus.  The same procedure was used for stripping the female and segregate of male.  The difference being only in the management method of temperature of water all along the flow through system.  The sketches of the both the models are given below.

 

Results and Discussion:

 

It was observed that the hatching percentage was increased by use of innovative model.  It was due to the fact that the water temperature could be maintained at 20 Degrees C during the hatching period in innovative model.  In case of CIFA model the hatching temperature could be maintained at 18 Degree C.  As is already discussed that the temperature of water is a one of the factor contributing to the hatching percentage and survivality of the hatchlings till it becomes fingerlings.  Thus, it can be concluded that the suggested innovative model may be implemented for production of larvae’s in Vidarbha region of Maharashtra and all such similar geographical locations.

 

Table: Observations recorded during the experimentation

 

Sr

Parameter

 

CIFA Model

Innovative Model

1

No of tubs used

 

5

5

2

Average inlet water temperature, Degree C

17

17

3

Fertilized eggs used in each tub

 

500

500

4

Hatched Larvae, Nos

 

325

375

5

Percent increase in hatching over the CIFA model

15.38%

 

References:-

 

1.      Allen,K.O., 1974. Effects of stocking density and water exchange rate on growth and survival of channel catfish.  Ictalurus puncticus in circular tanks.  Aquaculture, 4:29-39.

2.      Blaxter,J.H.S., 1969. Development: eggs and larvae. In: W.S.Hoar and D.J.Randall (Editors) Fish Physiology. Academic Press, New York, NY,pp.177252.  

3.      Haylor, G.S.,1992.  Controlled hatchery production of Clarias gariepinus (Bruchell, 1822): Growth and survival of fry at higher stocking density.  Aqucult. Fish. Manage., 22:405-422

4.      Khan, H.A., 1969.  Induced breeding of air breathing fishes.  Indian Farming.19:26-28.

5.      Khan, H.A., 1972.  Breeding catfishes under controlled conditions. In: CIRFI Silver Jubille Souvenir, Barrackpore,pp.73-78.

6.      Thakur,N.K. and Das P., 1986.  Synopsis of biological data on C.batrachus (Linn.1758) Bulletin No. 41. CIFRI Barrackpore.

7.      Tripathi, S.D. and R.K. Sharaf, 1974.  An artificial feed for air breathing fishes.  Labdev.J.Sci. Tech.  India., 12-B(4):151-152.

8.      Verghese, T.J., K.V. Devaraj and G.P.S.Rao, 1973.  Food of juveniles of the cat fish, Clarias batrachus ( Linn.).  J. Inland.  Fish.  Soc.  India. 5:78-81

 

 

About the Author

P.P.Shelke, SMS (Agril.Engg), KVK Karda

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