USE OF SEX-REVERSED FEMALES TO PRODUCE ALL-MALE TILAPIA (OREOCHROMIS-AUREUS) FRY

Oreochromis aureus fry were fed 17alpha Ethynyl Estradiol impregnated fish meal to reverse the sex of the males. The sex-reversed females (p henotypic females with a male genotype) were identified by mating them with normal O. aureus males and examining the percentage of males obt ained in the progeny. Of eight pair spawnings, two females produced 10 0% male progeny. These two females were bred again with males from the same O. aureus line. The all-male fry were treated with estrogen, res ulting in 185 phenotypic females with a male genotype. These fry were used as broodstock in commercial production trials which produced 98-1 00% all-male populations.