Three precautions should be taken for fish in winter.

In winter, there are few phytoplankton and poor oxygen production capacity in ponds with low water temperature and light, and fish are relatively weak due to less feeding and activity, which have a great impact on safe overwintering and growth. In order to ensure the safety and growth of fish in winter, the water quality control and management of fish ponds should be prevented in winter.

In order to prevent shallow water, some mariculturists think that the shallow water in the pond in winter is similar to fish. in fact, this is a misunderstanding. In winter, the pond water level is shallow, the water temperature changes rapidly and the temperature difference is large, which will cause frost damage to fish, which is extremely disadvantageous to the overwintering and growth of fish. In winter, the water level of fish ponds should not be lower than 1.5 meters, and the water level should be deepened to more than 2 meters in severe winter.

In order to prevent hypoxia, several kinds of ponds will also appear in winter: first, fish in fat-water ponds, second, fish in deep-water ponds, and third, fish cultured in cages. In these cases, fish often lose their heads due to lack of oxygen in winter due to neglect of management, or even die seriously, causing greater economic losses to breeders.

Measures to prevent anoxia of fish in winter: first, to control the breeding density of fish, especially in the waters of cage culture, the area of the cage should be controlled within 3% of the total water surface; second, timely fishing in winter to reduce the density of culture and reduce the load of water.

For the pond culture waters where hypoxia occurs, relevant methods can be taken to provide first aid: one is to pump water to increase oxygen, the second is to sprinkle long-acting oxygenating spirit, and the third is to use the oxygen in the oxygen bottle to oxygenate the fish in cages and high-density fish ponds through plastic pipes.

Cold winter often causes frost damage to overwintering fish species. The following four anti-freezing measures can be taken: first, set up barriers to increase temperature. In the north of the fish pond, wooden bamboo sticks are piled around woven bags or straw, and artificial barriers are set up to resist the north wind. The second is smoking to increase the temperature. The north wind whistling during the day is a harbinger of frost at night. Wet straw and firewood can be piled on the shore of fish ponds to make fire and smoke to create a warm atmosphere and reduce the degree of frost. The third is to throw grass to increase temperature. Put a certain amount of water and grass into the fish ponds in winter to keep the fish warm in the grass and drive out the cold. Fourth, water injection to increase temperature. Inject sun-heated shallow water into fish ponds on a sunny afternoon with high temperatures.