Fish Seed Production, Hatchery Management and Breeding
This domain covers broodstock, induced breeding, hatching and the seed stages from spawn to fingerling. The exam tests the sequence of hypophysation, hatchery operation and nursery management.
Core rules
- Select healthy, mature broodstock; identify sex by body shape and genital papilla. Keep males and females separately before breeding.
- Hypophysation uses carp pituitary extract or synthetic hormone. Dose is calculated per kg of broodfish, usually as a priming dose followed by a resolving dose.
- After injection, maintain broodfish in breeding hapas or tanks at suitable temperature; spawning occurs after a latency period.
- Incubate eggs in hatchery jars or tanks with gentle water flow. Remove dead eggs to prevent fungus.
- Seed stages: spawn (newly hatched), fry (yolk absorbed, starts feeding), fingerling (hardy, stocked in grow-out ponds).
- Transport seed in oxygenated bags or containers at safe density; avoid overloading.
Worked example
A 3 kg female is prescribed 5 mg pituitary extract per kg body weight. Calculate the dose. Reasoning: dose is per kg broodfish, so 3 kg × 5 mg/kg = 15 mg. Weigh the extract accurately and record the injection time. Do not multiply by pond biomass; only the treated fish’s weight matters.
Traps
Do not inject all fish with the same total dose regardless of weight. Do not confuse spawn with fingerling. Do not expose eggs to strong turbulence or direct sunlight. Do not stock fry before the yolk sac is absorbed and they are feeding.