What are the key technical points for autumn management of fingerlings?

In autumn, the weather turns cold and then warm again, and the water temperature is suitable. This is the peak season for fingerling growth. Doing a good job of autumn fingerling management is a direct means of improving economic returns. The author believes that the following tasks should be done well in autumn fingerling management techniques.

1. Clear the pond in time. Generally speaking, for ponds that have been used to raise fingerlings for 2 3 months, the water quality will deteriorate, natural feed will decrease, and harmful substances such as hydrogen sulfide and pathogenic bacteria will increase. After the beginning of autumn, fingerlings should be transferred to ponds that have been cleared and disinfected for cultivation. In places where there are difficulties in water source and pond turnover, all fingerlings can be transferred out for temporary holding, then the original pond should be disinfected with 75-100 kg of quicklime per mu, and water fertilization should be carried out according to conventional methods. After the medicinal effect disappears, the fingerlings should be transferred back to ensure the purification of the living environment.

2. Scientific feeding. In autumn, the climate is suitable, fingerlings have a large food intake and grow rapidly, so the supply of feed must be guaranteed. In fingerling ponds mainly for herbivorous fish and supplemented with silver carp and bighead carp, green feed should be the main feed, with an appropriate amount of concentrated feed. Each day for every 10,000 grass carp fingerlings, feed 70-90 kg of small duckweed, tender upland grass or aquatic grass, and 1.5-2.5 kg of concentrated feed.

Feed green feed first, then concentrated feed, to avoid grass carp competing for food with other fish. Feeding should ensure quality, quantity, timing and location. For mixed-culture silver carp and bighead carp, fertilizer should be applied regularly, once every 10-15 days, with 70-90 kg of fermented human and livestock manure per mu, and the pond water transparency should be kept at 30-35 cm. In fingerling ponds mainly for silver carp and bighead carp and supplemented with grass carp, fertilizer application should be the main method and feeding supplementary. In addition to applying base fertilizer, apply topdressing once every 5-10 days, with 80-100 kg of decomposed human and livestock manure per mu. At the same time, feed 2-4 kg of concentrated feed per 10,000 fingerlings each day. For the supplemented grass carp, before feeding concentrated feed, feed 60 90 kg of green feed per 10,000 grass carp.

3. Separate rearing management. Fingerlings should be reasonably separated and reared according to different specifications, so that the specifications of fingerlings placed in the same pond are consistent. Because large-sized fingerlings have a large food intake and strong ability to compete for food, if small-sized fingerlings are also placed at the same time, the small fish will decline in physique because they cannot get enough feed. Fingerlings above 16 cm can be placed in adult fish ponds for supplementary culture, while smaller fingerlings need to be cultivated in special ponds to avoid food competition and the extreme phenomenon of the strong becoming stronger and the weak becoming weaker.

4. Regular pond inspection. During the fingerling cultivation period, pond inspection must be carried out every day to observe the fish's feeding and living conditions, pay attention to changes in water quality, and frequently change new water, adding and changing new water once a week. Also frequently clean the feeding ground, promptly remove residual bait and leftovers, and every half month splash the area around the feeding ground with 0.5 kg of bleaching powder dissolved in water. Regularly feed medicated bait, preferably twice a month, for 3 consecutive days each time. If diseased fish or dead fish are found, they should be promptly removed and deeply buried, and diagnosis should be carried out at the same time, with drug prevention and treatment given.

5. Reasonable sparse stocking. Producing larger-sized fingerlings in autumn is an important part of improving the overwintering survival rate of fingerlings. Reasonable sparse stocking should be carried out according to conditions such as water surface size and water depth to promote fingerling growth. For a pond with a water depth of 1.5 m, stock 4,000-6,000 fingerlings of 7-8 cm per mu. When raised until the end of the year, the body length can reach 13 17 cm. This plays a very important role in improving aquaculture returns.