We demonstrated that the high-temperature treatment causes a complete sterilization in all age groups of the female Nile tilapia, O. niloticus, Chitralada strain and that this temperature-induced reproductive impairment occurs via induction of germ cell loss. Our results also provide insights into thermal regulation of reproductive physiology in fish. Future studies will investigate the possibility for sterility development in male tilapia and seek mechanistic explanation (both epigenetic and genetic) for high temperature induced germ cell degeneration and induction of sterility.