Introduction:
In the early days of induced carp breeding, there were only outdoor breeding and hatching facilities mainly comprising of cloth enclosures (called hapas) installed in ponds. The use of hapas involves mechanical transfer of eggs from breeding hapas to hatching hapas (Jhingran, & Pullin, 1985). But isolation and picking up the individual spawners latter becomes quite difficult in a community breeding tank whatever its shape, despite operating a dip net. Keeping this in background, Chinese hatchery was originated with various facilities like continuous water flow within a limited space, centrifugal force creates effective inlet and outlet, provides additional aeration which ultimately makes hatching more effective. But after all, the success and failure of a hatchery owner is very much dependent on hatchling care and also on his hatchery management technique.
Why hatchery?
In India, many farmers allow to hatch the eggs of carps (both IMC and Chinese carps) in stagnant ponds which often subjected to heavy predation and exposure to diseases due to infections and environmental hazards. It causes to the reduction of hatching percentage. For this reason, fertilized eggs are generally collected after water-hardening and moved to special incubation chamber for hatching. This incubation chamber may be traditional hatching hapas or may be cemented or fibered Chinese hatchery. Now, hatching of eggs in a pond-hatching device, like a hatching hapa, involves devastating consequences from a rise of water temperature to drop of water level which often lead to total mortality of hatchlings. In comparison to a hatching hapa, a Chinese carp hatchery is more efficient to maintain a running water supply as it is a flow-through system. Here, the rate of water flow, water temperature and dissolved oxygen content can be controlled and that ultimately leads to the control of bacterial and fungal infections.
Essential components of a hatchery:
Broodstock ponds’ to hold adult fish for spawning that serve as donors of pituitary glands and to accommodate spent females and males;
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‘Overhead tank’ for water storage and supply to the hatchery whenever is needed;
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‘Breeding pool’ may be either earthen pond or cemented tank or cemented cistern;
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‘Hatching pool’ may be cemented or fabricated portable FRP carp hatchery with a circular water flow system;
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‘Spawn collection chamber’ where spawns can be collected. It should be located at a level lower to the hatching pool;
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‘Nursery ponds’ for rearing post larvae to fry stage (not necessarily). If the business is only limited to the spawn production it is recommended to build ‘spawn storage tank’ at least for 3 days or unless it is marketed to the nursery owner.
Operational procedure of spawn production:
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The broodstock pond is prepared by liming and fertilization. By January/February, it should be stocked with required species.
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2-3 year old brood fishes that are weighted around 1.5-4.0 kg should be selected as brooder.
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Before putting the broodfish into the pond, they should be dipped in potassium permanganate solution.
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Every fortnight, the pond should be netted to check the condition of the fish and to keep brooders healthy. From the end of May or early June, breeders can be selected for spawning. But in the advancement of modern technology that is by using synthetic hormone (like spawnpro, ovatide, ovaprim etc.) brooders can be injected from March month onwards.
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Brooders then are carefully transferred to the breeding pool. The water in the breeding pool should be about 1 m deep. The broodfish should be stocked at about 3-4 kg/m3.
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The broodfish are then left in the breeding pool for acclimatization for about 4-6 hours. After this, the females are taken out, injected and returned to the pool. Four to six hours after this, then females are injected again. The males are also injected at this time, if necessary.
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A shower head above the breeding pool stimulates brooders.
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When the fish have spawned, the eggs are transferred to the hatching pool.
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Hatching takes 16-20 hours. The broken egg shells pass out through the nylon netting.
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After 72 hours the hatchlings (spawn) are collected in the ‘Spawn Collection Chamber’.
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After absorbing the yolk sac spawns can be reared in the nursery.
Conclusion:
With the increased commercialization of carp farming and greater market focus there is a need to increase the production of spawn in a rapid way which can be achieve through a proper hatchery management. One can take ‘spawn production of Indian Major Carps in Chinese hatchery’ as a business venture. They can start it by opening smaller hatchery unit (buy brooder fish from others and sell it with linking nursery owner or grow out farmer) and later expanded it in larger unit (have brooder pond and nursery pond). Proper knowledge on hatchery operation and adoption of scientific practices can make a hatchery owner to a successful entrepreneur.
Reference:
Jhingran, V. G., & Pullin, R. S. (1985). A hatchery manual for the common, Chinese, and Indian major carps (No. 252). WorldFish.
Authors details
1Soumili Das, Ph.D. Scholar, Department of Fishery Extension, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences
2Satarupa Ghosh, Ph.D. Scholar, Department of Aquatic Environment Management, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences
Corresponding email id: soumili.ext@gmail.com