Hormonal induction of sex reversal and progeny testing in the zebra cichlidCichlasoma nigrofasciatum

Hormonal sex reversal was induced in the ornamental cichlid C. nigrofasciatum by dietary administration of estradiol-β or 17α-methyltestosterone. The treatments involving 200 mg estradiol-β and 200 mg 17α-methyltestosterone/kg diet for 20 days in the 4-day posthatchling C. nigrofasciatum resulted in 100% feminization and 82% masculinization, respectively. Superoptimal doses led to higher mortality and stunted growth, especially among the surviving males, which resisted feminization. Progeny testing of the feminized and masculinized individuals indicated that sex was determined by XX and XY (male heterogamety) sex chromosomes; however, the role played by autosomes in these individuals was also apparent. Live homogamous males (YY) could not be produced. Progeny testing further showed that hormonal treatment impaired growth and reproductive performance of the sex-reversed females and males. F1 progenies sired by the sex-reversed females as well as males also suffered higher mortality, extended interspawning period and lower fecundity.