The present study exposed adult zebrafish to 0, 10, and 100 μg/L perfluorobutanesulfonate (PFBS) with or without dietary supplement of probiotic Lactobacillus rhamnosus. Interaction between probiotic and PFBS on sex endocrine and reproduction was investigated. It was striking to find that PFBS and probiotic coexposures almost ceased the fecundity, which was accompanied by disturbances in sex hormones and oocyte maturation in females. In contrast, probiotic additive efficiently antagonized the estrogenic activity of PFBS in males. For the first time, this study reported that probiotic heavily depended on sex to modulate the endocrine disruption and reproductive toxicity of aquatic pollutants. Copyright © 2020 American Chemical Society.