Three precautions against shallow water, hypoxia, cold injury and fish culture in winter

Fish culture

Prevention of shallow water: the overwintering pond is shallow, the water temperature changes quickly, and the temperature difference is large, which is disadvantageous to the growth of fish. When the water level drops, the density of fish increases, which is easy to cause hypoxia and make the fish stop growing or even die. Therefore, the water level of the fish pond should be kept normal in winter.

Prevention of hypoxia: under normal circumstances, anoxic floodponds mostly occur in high temperature in summer and autumn, and are rare in winter. However, under the conditions of fertile water fish ponds, deep pool stagnant fish ponds and cage culture, anoxic flooding ponds will also occur in winter. In the above-mentioned waters, with the decrease of air temperature, the surface water temperature decreases and the density increases, and the bottom layer is anoxic and anaerobic water floats, resulting in anoxia in the upper water body. In addition, when the illumination time is short in winter, the photosynthesis of phytoplankton in water weakens and the oxygen production decreases, which leads to the lack of dissolved oxygen in water. Therefore, timely measures to increase oxygen should be taken in these waters in winter to prevent dead fish from flooding ponds.

Prevent cold injury: in cold winter, overwintering fish species are vulnerable to cold injury, so it is necessary to avoid cold and increase temperature: (1) set up barriers to avoid cold. Pile in the north of the fish pond and put woven bags or straw curtains around it to ease the cold spell. (2) heating up with dung application. About 500 kg of rotten livestock and poultry manure is applied per mu of fish ponds, and the heat released by fertilizer fermentation is used to raise the water temperature of fish ponds. (3) smoking for heating. In winter, the north wind howls during the day, and there is often frost at night. Wet straw can be used to light fire and smoke on the shore to reduce frost. (4) put in aquatic plants. Put an appropriate amount of water and plants into the fish ponds in winter to protect the fish from the cold in the grass. (5) water injection to increase temperature. In the afternoon of a sunny day with high temperature, the water from the shallow pond with higher water temperature is injected into the fish pond to increase the water temperature of the fish pond.