Sex determination in fish is regulated by environmental and genetic factors, both of which can affect gonad differentiation and development. However, the way in which the environment affects gonad development-related genes to regulate the sex of fish remains unclear. Current studies suggest that high expression levels of the upstream genes sox9 and amh can induce primordium differentiation into spermatocytes in fish, sox9 promotes and amh inhibits spermatocyte proliferation, and elevated expression levels of the downstream genes ar and er can induce spermatocyte division, differentiation, proliferation, and spermatogenesis in fish. Exogenous estrogen inhibited the expression of sox9 and amh but induced ar and er at low concentration and inhibited them at high concentration. In conclusion, male sex differentiation in fish is regulated by sox9,amh, ar and er, and changes in environmental factors can affect the differentiation process. This report therefore reviews the upstream regulatory genes sox9 and amh and downstream regulatory genes ar and er and their relationships with sperm development. We also consider the effects of environmental factors such as stress on these genes and sperm structure, to explore sperm development and the gene-regulatory effects of environmental factors during this developmental process.