Finfish Breeding and Hatchery Management

Unit 3 - Breeding of major carps

3.5. Fish broodstock management and transportation of broodfish
Management of broodfish ponds

• Brood fish is a prerequisite for all induced breeding programmes, as it produces eggs and milt, which are required for the production of larvae.
• Proper brood-stock will lead to better breeding responses, increased fecundity, fertilization, hatching and larval survival rates and more viable fish seed.
• Hence, the subject of brood fish management has assumed great importance in hatchery management.
• The number of brood fish ponds depends on hatchery requirements.
• Large-scale of operation and sex-wise segregation of fish requires more ponds.

Carp broodfish pond

• Carp brood-stock ponds are generally large (0.2-2.5 ha), 1.5-2.5m deep, 30-40m wide, rectangular, seasonal or drainable and earthen in nature.
• Water inlet and outlet should be such that they simulate riverine/fluviatile conditions, which is the natural habitat of IMC and Chinese carps.

Source of broodfish
Since selective breeding and hybridization programmes of pedigreed fish are not carried out in fish seed farms, the source of future broodfish is stock ponds from the same farm or different farms or live adult of different species procured from capture fishery waters like rivers, lakes or reservoirs.

Care of broodfish

• The carp brood-stock pond should be prepared following standard procedure to ensure sustained production of zooplankton.
• The recommended stocking density of carp brood fish is 1,250-2,500 kg/ha, depending upon the species.
• While rohu and mrigal are stocked at a higher rate, catla is stocked at a lower rate since it requires more space for proper gonadal development.
• Stocking rates are manipulated to permit individual and collective care of broodfish, enabling them to get nutritional and environmental advantages for onset of right degree of maturity.
• During immature stage, feed the fish with a traditional diet consisting of rice bran and oil cake (1:1) at a feeding rate of1- 2% of body weight daily.
• During the maturing phase, feed the fish with a special feed containing rice bran, oil cake, fish meal, cereals, grams and mineral and vitamin mixture.
• Alternatively, one can use commercial floating pelleted feed (protein content : 30%)
• In addition to the artificial feed the grass carp is also given tender aquatic weeds/terrestrial grass.
• However, the breeding habits of some species like common carp demand their separation from other carp species due to their natural breeding in ponds with aquatic vegetation.
• As a result the common carp brood fish is segregated sex-wise and stocked in separate ponds to prevent accidental spawning in pond.
• However, the rest of the species can be stocked in a communal pond or stocked in separate ponds after species-wise and/or sex-wise segregation.
• Catla, in particular, needs to be separated from the rest of the species as it shows poor response to hormonal injection when stocked with other species.
• A gravid fish when held by hand with tail up should practically ooze milt and also ova.
• Paddle-wheel aerator, particularly in catla pond, can provide additional aeration, particularly during morning hours.
• Segregation of sexes at least one month before increases the affinity between male and female during spawning.
• Care should be taken to maintain water quality and plankton level by periodic manuring, i.e. at one tenth of the initial dose.
• Algal blooms and oxygen depletion are controlled by water exchange.
• Parasites and pathogens should be controlled by periodic checking of brooders
• Common parasites like Lernea and Argulus are common on major carps (catla is more susceptible) can be controlled by manually removing and disinfecting the affected fish with a solution of KMnO4 (about 5 ppm)