Key Technical Points for Autumn Release and Autumn Cultivation of Fingerlings to Ensure Survival

Doing a good job of intensive autumn cultivation of fingerlings is the key to improving their overwintering survival rate.

Improving the environment: before releasing the fingerlings, drain half of the original pond water, then add fresh water. Apply 150 kg of fermented manure per mu of pond, once every 9 days, for a total of 3-5 applications. Appropriately apply additional chemical fertilizers mainly of nitrogen and phosphorus; generally apply 1.5-2.5 kg of urea and 3-5 kg of superphosphate per mu of pond, once about every 7 days. After each fertilization, add fresh water to keep the pond water transparency at 20-30 cm. Every half month, dissolve 10-15 kg of quicklime per mu of water surface and splash it over the whole pond once.

For stocking fingerlings, ponds mainly for cultivating grass carp fingerlings can be polycultured with about 30% silver carp, bighead carp and other fingerlings; ponds mainly for cultivating silver carp and bighead carp fingerlings can be polycultured with 30% grass carp fingerlings. The ratio of silver carp to bighead carp fingerlings is 5:1. The stocking density should be determined according to conditions such as water surface size, water depth, fingerling size and feed supply. Generally, for a pond with a water depth of 1.5 m, stock 3000-4000 fingerlings of about 10 cm per mu. The size of the stocked fingerlings should be uniform.

Feed feeding: when raising grass carp and blunt snout bream fingerlings, pay attention to supplementing fresh green feed; when raising black carp fingerlings, more animal feed such as snails and clams should be added. For ponds mainly raising silver carp and bighead carp fingerlings, the fertility of the water should be moderate. For silver carp and bighead carp fingerling ponds, in addition to ensuring moderate water fertility, appropriate amounts of wheat bran, rice bran, cake meal, etc. should also be fed. Around Frost's Descent, when the water temperature drops, more concentrated feed should be added, and the daily feeding amount should be about 3% of the body weight of the pond fingerlings. As long as the water temperature is above 7°C, feeding should continue, and stopping feeding too early must be avoided, but fertilization and green feed feeding should be reduced as appropriate.

Fish disease prevention and control: persist in patrolling the pond in the morning and evening, regularly disinfect to improve the water body, and feed in a way that achieves fixed time, fixed location, fixed quality and fixed quantity, and promptly remove feed residues. Feed medicated bait 2 times a month, each time for 5 consecutive days. If fish disease is found, diagnose it promptly and treat it according to the symptoms.