The soil is the best for fish ponds, followed by stickiness, and sand is the worst. In fish ponds that have been raised for 1 to 2 years, the accumulated fish feed pellets, fish excrement, and organisms are mixed with sediment to form silt, which replaces the original soil. If there is too much sludge, the oxidation and decomposition of the organic matter will consume a lot of oxygen, which is easy causes hypoxia. Moreover, the anaerobic fermentation of organic matter will produce harmful substances such as ammonia and hydrogen sulfide after hypoxia, which affects the survival and growth of fish. Usually, when the fingerlings are stocked, the bottom of the pond should be kept with a thickness of 5cm of silt. It has a significant effect on supplementing the nutrients in the water and maintaining and adjusting the fertility of the water.