17α-methyltestosterone exposure disrupted growth, liver physiology and intestinal microbial on fish: A case study on migratory bony fishes (Takifugu fasciatus).

17α-methyltestosterone (17α-MT) is prevalent in the aqueous environment, but its toxicological profile remains incomplete. This study analyzed the effects of different 17α-MT concentrations on the growth performance, mortality, sex ratio, liver physiological metabolism, and intestinal microorganisms of Takifugu fasciatus, and on the microorganisms composition of its culture environment. Results showed that 17α-MT increased the male ratio and mortality but inhibited the growth of T. fasciatus. Meanwhile, 17α-MT induced oxidative stress and mitochondrial autophagy, changed lipid metabolism and inhibited triglyceride (TG) accumulation in the liver. 17α-MT altered the composition of the intestinal microorganisms, notably increasing the number of pathogenic bacteria. Additionally, the Firmicutes to the Bacteroidetes (F/B) ratio, associated with lipid metabolism, decreased with increasing 17α-MT concentration. Furthermore, 17α-MT disrupted the connection between the intestine microorganisms in T. fasciatus and the water column. This study enhances understanding of the effect of 17α-MT on T. fasciatus and the toxicological profile of 17α-MT.