Fish Breeding, Seed Production and Hatchery Management
What the exam tests
Breeding and hatchery questions test reproductive biology, induced breeding, seed stages and hatchery operations. You must know the difference between hatchling, spawn, fry and fingerling, and the sequence from breeder selection to stocking.
Core rules
- Indian major carps usually breed in the monsoon; induced breeding is used when natural conditions are absent.
- Hypophysation uses pituitary gland extract; synthetic GnRH analogues such as ovaprim are also used. Dose depends on species, sex, weight and product label.
- Select mature, healthy breeders; males are usually smaller and release milt when pressed gently.
- After injection, keep breeders in spawning tanks; strip eggs and milt, mix, and incubate in clean, flowing water.
- Hatchery stages: eggs, hatchlings, spawn, fry and fingerlings. Handle each stage gently.
- Maintain clean water, stable temperature and low ammonia; remove dead eggs.
Worked example
A 1 kg female gives about 1 lakh eggs; 70 percent hatch. Expected hatchlings = 100,000 x 0.70 = 70,000. To get 2,00,000 hatchlings, need 200,000 / 70,000 = 2.86, so at least 3 females, assuming similar performance. Reasoning: multiply eggs by hatch rate, then divide target by output per female.
Traps
Do not confuse spawn with fry. Do not use the same dose for male and female. Do not leave breeders unattended after injection. Do not assume 100 percent hatch.
Key facts
Assam’s hatcheries supply carp seed. Egg incubators may be circular or rectangular. Record injection time and temperature.