What are the measures for intensive autumn cultivation of fingerlings?

1. Improve the growing environment. After several months of rearing in the original fingerling cultivation pond, the water quality gradually deteriorates, which is unfavorable for fingerling growth. Measures should be taken to improve it. First, add fresh water: drain 1/3-1/2 of the original pond water, then add fresh water at the same temperature. Second, apply fertilizer: appropriately apply more fermented manure, generally about 150 kg per mu each time, once every 7-10 days, for a total of 500-750 kg, generally by placing small heaps or splashing over the whole pond. In addition, appropriately apply chemical fertilizer as a top dressing, generally 1.5-2.5 kg of urea and 3-5 kg of superphosphate per mu, once every 5-7 days. To prevent water quality deterioration, it is best to add fresh water once for every fertilization, keeping pond water transparency at 20-30 cm. Third, disinfect regularly: every half month, use 10-15 kg of quicklime per mu and a bleaching powder solution at a concentration of 1 ml/kg, alternating and splashing over the whole pond once.

2. Adjust fingerling size composition. In ponds mainly cultivating grass carp, 30% silver carp and bighead carp fingerlings can be added. In ponds mainly cultivating silver carp and bighead carp fingerlings, 30% grass carp fingerlings should be added. The ratio of silver carp to bighead carp is 5:1. If bighead carp are small in size, the proportion should be reduced further. Stocking density should be determined according to the size of the water surface, water depth, fingerling size and feed supply conditions. Generally, for a pond 1.5 m deep, stock 3000-4000 fingerlings of about 10 cm per mu.

3. Ensure adequate nutrition. From the Beginning of Autumn to White Dew is the stage when fingerlings transition in feeding, so the amount of bait should be strictly controlled, with fish fed to about 80% full. Grass carp and Wuchang bream should be given supplementary fresh green feed, and black carp should be given more crushed snails, clams, etc. Ponds mainly raising silver carp and bighead carp are best kept moderately fertile. After the Autumn Equinox, it is still a golden period for fingerling growth. For feeding fish, sufficient suitable feed should be provided. For silver carp and bighead carp, in addition to ensuring moderate water fertility, an appropriate amount of wheat bran, rice bran and crushed oilseed cakes should also be fed. Around Frost's Descent, when temperatures drop, feeding should be increased, green feed appropriately reduced, and the amount of fertilizer applied to the pond should also be lowered. The daily amount of concentrated feed should be about 3% of the pond's fingerling biomass. Feeding should continue as long as the water temperature is above 7°C.

4. Strengthen water quality regulation. In early autumn, the weather is changeable. To prevent oxygen deficiency in the pond, water exchange should be strengthened. Generally change the water once every 7 days. Around the Autumn Equinox, when the weather turns cool, water can be changed about once every 10 days. For silver carp and bighead carp fingerling ponds, water transparency should be kept at 20-25 cm, while for grass carp, bream and carp fingerling ponds, water transparency should preferably be kept at 25-30 cm.

5. Do a good job in fish disease prevention and control. Persist in patrolling the pond morning and evening, and take timely measures when problems are found. Regularly disinfect the water body, feed bait at fixed times, fixed locations, with fixed quality and fixed quantity, and promptly remove leftover bait and residues. In addition, feed medicated bait twice a month, each time for 5 consecutive days. Mashed garlic and Chinese chives can be added to the bait at a ratio of 0.5 kg per 100 kg of fingerlings, which can prevent common diseases such as bacterial gill rot, hemorrhagic disease and enteritis.