Will fish die because of the cold weather?

When the temperature drops, the water surface in direct contact with cold air in rivers and lakes dissipates heat faster. When the temperature of water is above 4℃, the water with lower surface temperature will shrink in volume and increase in density due to thermal expansion and contraction, so it will continue to sink, and the water with higher bottom temperature will keep rising, forming a convection phenomenon. In this way, the upper part is cold, and the hotter water below will reach a uniform temperature.

If the temperature continues to drop, when the water on the surface cools below 4℃, it will shrink and expand, the density will become smaller, stay on it, stop falling and finally form ice. The ice layer is not good at heat conduction, so the water below is not easy to cool. In this way, the deeper waters will not always freeze to the end, and the water at the bottom of the ice can be kept at 4 C. The ice layer above is like a thick ice blanket, which keeps the fish and shrimp under water safe for the winter.

Extended data:

Precautions:

1. In order to ensure the safe overwintering of fish, the pond must maintain a deep water level. According to the temperature and water depth in our area, it should be 1.5 ~ 2 meters, and the minimum should be no less than 1.5 meters. If the water level is lower than this level, the water level should be deepened in time.

2. The method of adding water is to add 5 ~ 10 cm of fresh water every 7 ~ 10 days. If a fish is found to have a floating head, in addition to changing water and replenishing fresh water, it is also necessary to start the aerator in time or apply a chemical aerator to aerate.

3. Fertilization in ponds should be mastered according to the transparency of water. If the transparency of water is about 30 cm, it means that the water body is moderately fat and thin. If the transparency exceeds 45 cm, the water body is too thin. If it is a fish pond in the same pond, it should be topdressing with inorganic fertilizer. The application amount depends on the transparency of the water body. If the pond is empty, 150 ~ 200 kg of decomposed human and animal manure should be applied per mu, which will be used as base fertilizer after disinfection in the pond.

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