Mating behavior of a freshwater goby Eleotris oxycephala was observed 1-day after the injection of human chorionic gonatropin. Such behavior began with a female visiting a nesting male, which there upon courted the former. During mating, the nuptial coloration in both sexes changed, becoming dark-brown and light-brown in the female and male, respectively. Both sexes showed erection of the genital papilla, that in the female spawning eggs in a single layer on the substratum, and in the male releasing sperm on the eggs. The number of eggs laid by a single female was estimated as being from 35, 000 to 190, 000.
