Abstract: In recent years, the intensive breeding mode has developed rapidly, however, various problems emerge with intensive fish culture methods, especially crowding stress and increased susceptibility to disease, which will ultimately influence the growth performance, welfare, and profitability of the farmed fish. Intestinal microbes play an important role in maintaining the balance of intestinal environment and host health. We are genuinely concerned about the health of fish (via their intestinal flora) under high density culture. Therefore, the present study aimed to describe compositional and functional differences of the gut microbiome of genetically improved farmed tilapia (GIFT, Oreochromis niloticus) reared under Acanthopanax senticosus ultrafine powder, by investigating their responses to 8 weeks culture experiment. The results showed as follows: (1) adding 4‰ A. senticosus superfine powder to the diet could significantly increase the activities of intestinal amylase, lipase and trypsin, improve the growth and development of tilapia and improve the feed conversion rate. (2) adding 4‰ A. senticosus superfine powder to the diet could significantly reduce the levels of triglyceride and total cholesterol in the liver, and reduce the content of malondialdehyde and increase the activity of superoxide dismutase in the liver. (3) adding 4‰ A. senticosus superfine powder to the diet could significantly affect the composition of intestinal microorganisms and improve the alpha diversity of intestinal microorganisms. Some diversity indexes are significantly positively correlated with amylase, lipase and superoxide dismutase, and negatively correlated with triglyceride and total cholesterol. (4) Proteobacteria, Fusobacteria and Firmicutes were the dominant phyla in the intestinal tract of GIFT. The core difference genera screened were Enterovibrio, Cetobacterium and Grimontia, which were significantly enriched in the control group. In addition, Lawsonia, Acinetobacter, Pseudomonas and Brevinema were significantly enriched in 4‰ A. senticosus adding group, indicating that there may be a certain abundance of potential pathogenic bacteria in fish during the growth cycle. Functional prediction analysis with PICRUSt2 revealed that the bacterial community was active in metabolism at hierarchy level 1. The relative abundance of human diseases in the control group was significantly higher than that in 4‰ A. senticosus adding group. Further, the abundance of functional genes was similar at hierarchy level 2, implying abundant functional diversity. In conclusion, adding 4‰ A. senticosus superfine powder to the feed could affect intestinal enzyme activity, liver biochemical indices and intestinal microflora composition and function of GIFT, and promote the healthy growth of fish.