The water quality deteriorated after freezing civilization in winter.

The general reason of water quality aging: 1, insufficient water. Winter rainfall is generally less, and the impact of water shortage is more obvious.

The water quality is very poor. In winter, the water quality of ponds is aging, and a large number of toxic and harmful substances such as nitrite and ammonia nitrogen often accumulate in the bottom water, which affects the survival of fish, shrimp and crabs.

3, easy to lack oxygen. The light time is short, the algae reproduction and photosynthesis are not strong, and the dissolved oxygen content in the aging water body is obviously reduced. If it is rainy, the air pressure drops, and the water is more likely to return to the bottom due to lack of oxygen.

4. Especially in high-density aquaculture ponds, the residual bait and feces deposited at 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, sulfite and hydrogen sulfide. Once the weather changes, it is easy to have poisoned floating heads and dead fish due to lack of oxygen.