Abstract

The study was carried out in the genetics and breeding resaerch canter of yasouj. All eye-stage eggs were used for the experiment using vertical hatching units to complete hatching. A standard commercial granule feed was used in all experimental groups. The experiment consisted of control treatment and one dose of hormone 17α- Methyltestosterone added to the diet at the rate of 3 mg per kg food by dissolving in 200 ml of 95% ethanol per kg feed.The use of oral administration of 17α- methyltestosterone (17MT) at 3 mg 17MT/kg of feed for 70 days following the onset of feeding to sex reverse rainbow trout (Oncorhynchus mykiss) to produce XX males is well established. Examination of the results showed that 17α- methyltestosterone was effective in sex riversed of rainbow trout. The results has shown in nearly 100% of the treated animals being males. The GSI index in female and male fish of control group were 0.04±0.1 and 0.07±0.01, respectively (Fig.3) and significantly different (p≤5%). But GSI index of 100% sex riversed male fish of MT treated was 0.06±0.01 and hadn,t significantly differene (p≥5%) with treated group ( genetically male and female).

Keywords: Onchorynchus mykiss, 17α-Methyltestosteron, Sex reversal, GSI index, XX male