Observation On Aquarium Spawning Of Estrogen-Treated And Untreated Tilapia

Genotypic male Tilapia aurea, previously treated for sex reversal to a female state, and their sex-reversed female (F') parent were stocked into aquaria with untreated females at various ratios. The reproduction of the 2 types of females with normal males was compared. None of the treated fish spawned; most were later found to have ovotestes. The PI sex-reversed female spawned repeatedly after she was paired with a male in a larger tank, indicating that the presence of normal females under confined aquarium conditions may have a repressive effect upon estrogen sex-reversed females.