What should be paid attention to when releasing fish fry in winter in the reservoir

Every winter is the golden season for releasing silver carp, bighead carp, grass carp and herring to the reservoir. However, many households reported that a large number of dead fish and swimming diseased fish would be found on the water surface of the reservoir within two to seven days after the fish were released. The skin of these fish lost their luster and their body surface mucus increased. According to the above symptoms, it can be inferred that the fish is suffering from a typical "incompatibility of soil and water". The disease is mainly caused by drastic changes in water temperature and strong stimulation of nerve endings in the skin of fish, resulting in internal organ dysfunction. The mortality rate is as high as 20%-60%, causing serious economic losses to fishermen. So, how to prevent the occurrence of the disease?

1. Adjust the temperature difference. The cage is placed in advance at the bay of the reservoir. When the difference between the water temperature of the fish pond and that of the reservoir is more than 3 ℃, the temperature difference should be adjusted gradually. After the fish species adapt to the water environment of the reservoir, the fish species should be put into the reservoir. The method is to gradually add reservoir water to the tank carrying fish fingers. when the water temperature in the tank to be loaded with fish species is close to the water temperature of the reservoir, stay for another 10 ~ 30 minutes, and slowly pour the fish species and water into the cage to adapt to the new water environment. After being temporarily cultured in the cage for 120 minutes, the fish species can swim freely into the reservoir.

two。 Drug prophylaxis. According to the characteristic that the water temperature of the reservoir is often lower than that of the fish pond, the method of garlic juice combined with urea can be used to prevent the "soil and water insufficiency" of fish species, which has a very good effect and does not have any side effects on fish species. Add 1.3 kg garlic paste to every 500 kg of water, and after the fish are loaded into the tank, use 2.5 kg of urea in every 500 kg of water to sink to the bottom of the tank. When urea slowly dissolves, it absorbs the heat of the water in the tank and slowly lowers the water temperature in the fish transport tank, which helps the fish species adapt to the lower water temperature environment.