Although there are few fish diseases in winter, it is difficult to find the main management points of fish overwintering.

Fish overwintering

First, do a good job of fish physical examination to prevent sick fish from overwintering:

With the decrease of water temperature, the microbial reproduction weakened, and the fish disease decreased obviously before and after overwintering, but some fungi and parasites adapted to low temperature were still lurking in the water, which could lead to water mildew and Gill rot at any time, especially in the fish ponds after pulling the net. However, due to the weakening of fish activity and the influence of water temperature in winter, it is difficult to find diseased fish on the water surface. If fish disease is found after the pond freezes, it will be troublesome to be treated again, and the treatment effect is poor. Therefore, the use of medicine in fish ponds should be done before overwintering. The method is: in the warm afternoon mu with 200 grams of bromochlorohydantoin sprinkled, after 2-3 days, mu with 200 ml wheel (matrine) sprinkled, can effectively prevent diseases.

Second, increase fish body fat and improve fish physique:

Overwintering fish have varying degrees of weight loss, the four domestic fish can generally reduce by about 5%, especially grass carp and mackerel, the decline is even greater. This is because the fish go into semi-hibernation after they stop eating. Although a large amount of energy is not needed because of low temperature, there is still some activity, which makes the viscera of fish still need some energy to maintain life. Therefore, some high-quality concentrate feed, such as carp with more than 32% protein and grass carp with more than 28% protein, should be properly fed within 20 days or even a month before the fish stop eating. It is best to add about 5% corn to the feed to increase the effective sugar content of the feed, so as to increase fish fat and increase the thickness of fish muscle, which can avoid frostbite caused by severe cold and effectively reduce the problem of "losing fat".

Third, strengthen the management of pool water and improve the quality of water body:

After the fish pond is frozen, the water temperature at the bottom is not necessarily low, and the residual bait, feces and phytoplankton deposited on the bottom of the pond are still fermented and decomposed, which not only consumes dissolved oxygen in the water, but also produces harmful substances such as ammonia nitrogen and hydrogen sulfide. In addition, the factors such as low temperature in winter, short illumination time, the decrease of microorganisms and the decrease of dissolved oxygen make the harmful substances difficult to decompose, so it is more difficult to eliminate harmful substances in water at low temperature than in summer. Therefore, when the water temperature of the overwintering pond is not lower than 18 ℃, sprinkle it with 0.5 kg of biological agent EM per mu, or 1 kg of "magnetic water quality improver" (aluminum sulfate and strong body compound). When the fish stopped feeding completely, 150 mu of "rotifer Kuaike" (the main ingredient acetic acid) was used to prevent the excessive occurrence of zooplankton in the water, so as to ensure the quality of overwintering water.

Fourth, postpone the time to stop eating and feed reasonably in winter:

The common warm-water fish stop feeding obviously when the water temperature is below 10 ℃, and most of the agriculture and fisheries no longer feed. However, experiments show that these fish are given a very small amount of bait every day and can still be swallowed quickly in a short period of time. Thus it can be seen that the later the fish stop eating in winter, the better, even after stopping eating, camping on a sunny afternoon to feed a small amount of feed.

Fifth, do a good job in increasing oxygen in water bodies to ensure safe overwintering:

As the water surface is frozen, in order to allow the fish to survive the winter safely, it is recommended that the aerator be shifted to the vicinity of the feeding platform before freezing, and the aerator should be turned on regularly for about half an hour every day, so as to ensure that the area near the aerator will not freeze even if it is severe cold. in order to achieve the purpose of long-term ventilation and improvement of dissolved oxygen in the water body under the ice. In addition, for seepage ponds, new water should be injected regularly to ensure that the depth of ice is 1-1.5 meters. When adding water, add from the bottom up, do not form two crops of ice, to prevent fish frostbite frostbite to death. At the same time, clear the snow reasonably in the heavy snow day to ensure the photosynthesis of phytoplankton under the ice.