Effect of 17-alpha-methyltestosterone on neomale broodstock production process from native and imported hatched rainbow trout eggs

The production of all-female monosex rainbow trout through the production of sex reversed male breeders by hormone therapy has several advantages, and in previous years, delays in the localization of this technology has led to the country's dependence on imported eyed eggs. In this research, the native rainbow trout fry and the fry from all-female imported eggs were fed with a diet containing 3 mg/kg of the hormone for 70 days in order to make it possible to use the imported fish stocks for breeding and also the appropriate concentration of hormone therapy using 17 alpha-methyl testosterone. The results showed that all native fish were sex reversed to male and half of the breeders (XX male) were able to produce the gynogene sperm, exclusively. The results of hormone therapy of fish produced from the imported all-female eggs were about 57% male and 43% female. The male fish at age 22 months were neomale (sex reversed male) and capable of producing sperm and fertilizing eggs but female fish had undeveloped and small ovaries. In addition to the indirect production of all-female fish, this study can facilitate the use of the genetic potential of the fish from imported monosex all-female eggs through sex reversing and mate with native fish stocks and increase the genetic diversity of progenies of native fish stocks that be used in base population production in breeding programs and cold-water fish farms.