Antibiotic accumulation, growth performance, physiologic status and intestinal flora diversification of Nile tilapia (Oreochromis niloticus) feed by diets supplemented with different dose of sulfamethoxazole

Abstract Background Sulfamethoxazole (SMZ) is an antibiotic used globally to treat fish disease in aquaculture, but the effects of exposure to legal aquaculture doses of SMZ in fish are still unclear. To comprehensively investigate the effects of exposure to legal doses of sulfamethoxazole (SMZ) in Nile tilapia (Oreochromis niloticus), fish were exposed to diets supplemented with different doses of SMZ (blank group, normal feed; LS, 0.67 g/kg; MS, 6.67 g/kg and HS, 33.33 g/kg) for 4 weeks. General SMZ accumulation, growth performance, physiologic status, intestinal and hepatic health were systemically evaluated. Results The exposure experiment indicated that the SMZ accumulation in O. niloticus muscles, intestinal and aquaculture environment were positively related to the exposure dose. And withdrawal of antibiotics feed after 4th week, the SMZ residual in fish muscles, aquaculture water and sediment gradually decreased to safe level. LS and MS amount of antibiotics promoted the growth of fish accompanied by reduced feed coefficient in treated groups, while the fish growth in HS group was retarded. Exposure of O. niloticus to SMZ also increased the content of TG, promoted liver hypertrophy, and increased number of fat particles in liver. Antibiotics changed the content of intestinal short-chain fatty acids (SCFAs), and the changes in acetic acid were the most obvious. SMZ exposure reduced the biological diversity of the intestinal flora subsequently induced microbiota dysbiosis, and the degree was positively related to the exposure doses, and the experimental mainly inhibiting the growth of Fusobacteria. Conclusions Overall, exposure to of fish to legal doses of SMZ impair general physiological functions, intestinal flora and provokes health risk in fish. This study highlights the importance of rational and regulated use of SMZ in aquaculture.