Document Type : (original research)
Islamic Azad University branch Bandar Gaz
Department of Fisheries, Faculty of Natural Resources, University of Guilan, Sowmeh Sara, Iran
Fish sterilization methods are normally used aiming increase growth rate and avoiding early and undesirable breeding. Sex reversal and sterilization due steroid hormones are some of the most common methods in ornamental fish aquaculture. Also, the difference in the sensitivity of livebearer and oviparous fish to hormone treatment has been well discussed previously. Therefore, the present study was conducted with the aim of comparing the sterilization due oral treatment of 17-alpha-methyl testosterone (MT) in the livebearer Poecilia reticulata and the oviparous Cichlasoma nigrofasciatum. Guppy and Cichlid fries were divided into seven groups, these groups were fed at the first external feeding by commercial diet contains 30, 60, 100, 150, 200, 300 and 0 (control) mg of hormone 17 alpha-methyl Testosterone per kilogram of food respectively, 6 times a day for 40 days. Each treatment was performed with three replications. The hormone was added to the food by alcohol dry method. After the hormonal treatment period, the gonads of the fish were examined histologically. The obtained results showed that in the studied cichlid 300 MT hormone per kg of food resulted in 97.6% of sterilized individuals, which had a significant difference with other treatments (P <0.05). Also, in guppy 300 mg of hormone per kg of food resulted in 37.7% of sterilized individuals, which had a significant difference with other treatments (P <0.05). The results showed that there is a direct and significant relationship between increasing the concentration of hormone and production of sterility.