Production of ZZ females in the female-heterogametic black molly, Poecilia sphenops, by endocrine sex reversal and progeny testing

Feminization was achieved in the female-heterogametic viviparous P. sphenops by administering 200 mg beta-estradiol or diethylstilbestrol per kg diet to newly born fry for 30 days. Treatment with the optimum dose of beta-estradiol led to the production of a single homogametic (ZZ) female, which when crossed with a normal male, sired an all-male progeny. A comparison between production of P. reticulata homogametic males and homogametic P. sphenops females indicated that the treatment with the optimum dose of beta-estradiol enhanced survival and production of 'supermale' (YY) in P. reticulata or 'superfemale' (ZZ) in P. sphenops. Hence, amenability of female-heterogametic viviparous fish to induced sex reversal is comparable with other species. However, P. sphenops suffered higher mortality and lower fecundity than P. reticulata.