When does the phenomenon of fish floating head usually occur?

In summer, fish floating head usually occurs at night, especially in the early morning.

Hot and rainy days in summer are particularly easy to cause fish to float or even flood the pond, which will affect the growth of fish and even lead to the death or even extinction of fish.

The reason of fish floating head. 1. The floating head is caused by severe convection caused by the temperature difference between the upper and lower water layers. On sunny days in summer, the water quality of intensive fish ponds is strong, and there is a great difference in dissolved oxygen between the upper and lower water layers during the day. In the afternoon, the upper water layer produces a large amount of oxygen surplus, and the lower water layer produces a large amount of oxygen debt. Due to the thermal resistance of water, the upper and lower water layers are not easy to convection. In the evening, the subsequent thunderstorm or strong wind caused the surface water temperature to drop sharply, resulting in density current, which caused the upper and lower water layers to convect sharply. The water with higher dissolved oxygen in the upper layer quickly flowed to the lower layer, which was quickly consumed by the organic matter in the lower water, and the oxygen debt was paid off, so that the dissolved oxygen in the whole pond dropped rapidly, resulting in anoxic floating head. 2. In summer, in case of continuous rain or fog, the floating head caused by weak photosynthesis, poor lighting conditions, weak photosynthesis intensity of phytoplankton, low supply of dissolved oxygen in the water, and continuous consumption of oxygen by various biological respiration and organic matter decomposition in the pool, resulting in insufficient supply of dissolved oxygen in the water, resulting in floating head of fish. 3. Because the water quality is too thick or deteriorated, it doesn't rain on the floating head for a long time in summer, and the temperature of the pool water is high. If a large amount of bait is fed, the water quality is fatty and the oxygen consumption is high. Due to the low transparency of water, shallow oxygen-rich water layer, high oxygen-consuming water layer and insufficient supply of dissolved oxygen in water, it is easy to cause fish to float. If this kind of water quality is not replenished with fresh water in time, the water color will turn black, which will easily cause all plankton in the water to die of hypoxia. When the water turns clear and is accompanied by foul smell (commonly known as foul water), it often leads to the death of fish in flooded ponds.