Abstract: At present, the scale of the development of the shrimp and rice farming is getting larger and larger. Due to the uneven level of aquaculture, excessive feed feeding is a serious phenomenon, which increases the risk of eutrophication of aquaculture water. In this experiment, microbial nutrient was used to replace part of the feed. The results showed that after adding microbial nutrient, the crayfish production was reduced by an average of 139.5 kg per hectare, and the pH value of the aquaculture water was increased, and the dissolved oxygen content of the water increased by 0.15 mg/L. The content of ammonia nitrogen and nitrite decreased by 0.09 mg/L and 0.006 mg/L, respectively. But the total phosphorus content was increased, and the average increase was 0.17 mg/L. It indicates that the microbial nutrient can stably maintain the pH value of the aquaculture water in a weak alkaline environment, increase the dissolved oxygen content of the water body and reduce the content of ammonia nitrogen and nitrite substances in the water body, and create a suitable water environment for the healthy growth of crayfish, and increase the metabolic intensity of crayfish, promote the increase in food intake of crayfish and accelerates the growth.

Key words: shrimp and rice farming, microbial nutrient, water quality, yield