Masculinization Of Genetic Females Of The Common Carp (Cyprinus Carpio L.) By Dietary Administration Of An Aromatase Inhibitor

Abstract

In the present study, we demonstrated the ability of Fadrozole, an aromatase inhibitor, to induce sex inversion of genetically female common carp fry during the critical sex differentiation period. Thirty-day-old female fingerlings with a mean initial weight of 4.0 g (experiment I) and 3.5 g (experiment II) were fed a diet containing Fadrozole for 36 or 50 days, respectively. Not a single male was found in the control groups of both experiments. In experiment I, Fadrozole at 200 mg/kg feed resulted in 58.6% males, while fish receiving 17α-methyltestosterone at 50 or 100 mg/kg feed resulted in only 5-10% males. In experiment II, the efficiency of Fadrozole was dose- dependent; the lower dose of 100 mg/kg caused masculinization in 86% of the treated fry while the higher doses of 200 and 400 mg/kg feed increased the percentage of males to 97%. These results confirm the importance of aromatization during the labile period in common carp since low aromatase activity during this period, regardless of genotype, resulted in masculinization.