Research Article: Effect of ۱۷α-methyl testosterone, tamoxifen, and letrozole on growth performance and sex reversal of rainbow trout (Oncorhynchus mykiss)

Sex reversal and producing a monosex population is one of the most preferred growth promotion techniques of rainbow trout culture. Thus, the effects of ۱۷α-methyltestosterone (۲ mg/kg), tamoxifen (۲, ۲۰, and ۱۰۰ mg/kg), letrozole (۲, ۲۰, and ۱۰۰ mg/kg), and a combination of tamoxifen (۱۰۰ mg/kg) and letrozole (۱۰۰ mg/kg) on growth, masculinization and serum steroid content of rainbow trout were investigated in this research. Ethanol-dissolved chemicals were sprayed on commercial trout diet, and ethanol was evaporated overnight. The fish were fed the treated diet for two months and afterward, they were fed a commercial diet for six months. Results showed that ۱۷α-methyltestosterone reversed the sex of rainbow trout effectively. The proportion of males, intersex, and females in this group were ۷۶.۶۷%, ۱۰%, and ۱۳.۳۳%, respectively. In contrast with ۱۷α-methyltestosterone, using tamoxifen and letrozole showed no effect on sex reversal of rainbow trout. Growth performance was adversely affected by all chemical-treated diets. However, compensatory growth occurred during first month after ending treatment period.

Keywords:

Masculinization , Rainbow trout , Sex reversal