samples were collected during the migration flood season of 2017. After dissection, six samples of were selected as the infected group, and six samples that were uninfected were selected as the control group to determine the effect of C. nasus. A total of twenty-three bacterial phyla were identified. Twenty-two phyla were identified in the control group and eighteen phyla were identified in the infected group, among which Verrucomicrobia was only detected in the infected group. The main bacteria phyla in the intestinal tract of were Proteobacteria, Firmicutes, and Tenericutes, with a total relative abundance of more than 85%. The average content of Firmicutes, Fusobacteria, and Fibrobacteres in the infected group was higher than that in the control group, and the relative abundance of other bacteria phyla was lower than that in the control group, but there was no significant difference between the two groups ( > 0.05). Comparison of the relative abundance of bacteria at the family level showed that the proportions of Clostridiaceae, Peptostreptococcaceae, Lactobacillaceae from Firmicutes, and Enterobacteriaceae in the Proteobacteria were higher than those in the control group. Abundance of Peptostreptococcaceae, Lactobacillaceae, and Enterobacteriaceae in the 130 families identified were higher than those in the control group. Porphyromonadaceae and were significantly more abundant in the intestinal tract of the infected group ( < 0.05). At the community diversity level, there was no significant difference in Shannon index, Chao1 index, and Simpson index between the two groups ( infection on the community structure and species diversity of intestinal microorganisms were not significant, there were significant differences in the composition of specific species.