The Israeli Journal of Aquaculture - Bamidgeh 55(4), 2003
The 7th Annual Dan Popper Symposium


SEX-REVERSAL OF GENETICALLY FEMALE COMMON CARP  (CYPRINUS CARPIO L.)BY DIETARY ADMINISTRATION

OF AN AROMATASE INHIBITOR


Tatyana Zak¹, Ofer Sachs¹*and Itai Tzchori²

1 Aquaculture Research Station Dor, Ministry of Agriculture and Rural Development, 30820, Israel

2 Department of Zoology, George S. Wise Faculty of Sciences, Tel Aviv University, Tel Aviv, Israel


Abstract

The influence of a nonsteroidal aromatase inhibitor (Fadrozole™) on a genetically female population of Cyprinus carpio was studied. Fry were treated by dietary administration of an aromatase inhibitor during sexual differentiation (30 and 23 days after beginning exogenous feeding) and in an average temperature of 25±1.5°C (Exp I) or 28°C with fluctuations up to 35°C (Exp II). The duration of the treatments was 40 days in Exp I and 36-50 days in Exp II. At 25°C, the aromatase inhibitor (200 mg/kg feed) resulted in greater masculinization of females than methyltestosterone (58% and 3-6%, respectively). In Exp II, masculinization of females was even better: 63-100% males at a dose of 100-400 mg Fadrozole per kg feed. Masculinization was not observed to be dose-dependent. Within each treatment there was a positive correlation between the final weight of the fish and the proportion of masculinized fish. The greater masculinization of genetic females at the higher temperature probably indicates the presence of a temperature-dependent mechanism in sex determination.

*email: oferz@moag.gov.il

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