Broodstock Management

• Brood fish means the male and female fish which are used for breeding and seed production. Complete sexual maturity of the brood fish as well as good health is the most important factor for successful induced breeding operation. A good stock of brood fish raised through proper nutrition and care is the key for higher and better production of the stocking material of the cultivable carps.
• Use of own farm raised brooders for seed production is more convenient. However, to avoid inbreeding depression intermittent replenishment with brooders from other sources or from nature is recommended for commercial seed production.
• Brooders should be stocked in specially earmarked and prepared ponds for the purpose.
• The brooder ponds are generally more than o.15 ha area with a depth of 2.5-3.0m. The water depth should be maintained at 1.5-2.5m.
• The best time for collection and stocking of brooders is during the months from November to January.
• The optimal rate of stocking is 2,000-2,500 kg fish ha-1

Brood pond preparation and management

• Water replenishment or freshwater recirculation is advisable for maintaining the water quality particularly the dissolved oxygen content.
• Other management practices like maintaining water depth, deweeding, monthly liming and manuring as well as health monitoring are essential steps for proper management of the brood stock.
• The brooders ponds should be prepared before stocking with application of lime and manure to maintain the water quality as shown below, on the basis of soil and water quality status of the pond.

Dosage of liming material on soil pH status

Methods of application

Followings are some of the most effective methods:

(1) Lime should be applied in split-up dose and it is dangerous for fish if the amount for the year is applied as a single dose. Normally 25-30% of the total requirement is applied during pond preparation to dry bottom raked/wet bottom soil. Remaining quantities of lime is applied in equal monthly instalments and 7 days prior to application of manures, specially phosphate fertilizers.

(2) Dry bottom of ponds is treated with powdered slaked or quick lime to disinfect and reduce acidity of the soil. In case of water filled ponds if these two liming materials are to be used they be pre-dissolved to liquid state in a container and after the exothermic reactions, dispersed over the water surface.

(3) Required quantities of Agricultural lime or dolomite are normally applied on plate forms raised 15-30cms underneath surface water as a pile/heap in the wind-ward direction to facilitate slow melting of lime over a period of time and gradual mixing with water.

Fertilization

Feeding for brood fish

• For brood fish other than grass carp, supplementary feed prepared by mixing deoiled rice bran and oil cake @ 1:1 ratio or balanced, ready to use formulated feed @ 3-5% of the body weight of fish stock is recommended.
• For proper nutrition management, the supplementary feed provided should have 28-30% protein content especially during the advanced stage of maturation.
• Grass carp may be fed with submerged aquatic vegetation as well as terrestrial grass etc. at the rate of 1-2% of the body weight for acceleration of gonadal development. However, 3 months ahead of breeding programme foliage diet is completely withdrawn and fishes are fed with conventional diet @ 3-5% of the body weight of fish.