Comparative sterilizing between livebearer and oviparous fishes by oral treatment of 17α-methyl testosterone; case study on guppy (Poecilia reticulata) and convict cichlid (Cichlasoma nigrofasciatum)

Fish sterilization methods are normally used aiming increase growth rate and avoiding early and undesirable breeding. Sex reversal and sterilization due to steroid hormones are some of the most common methods in culture of ornamental fish. Also, the difference in the sensitivity of livebearers and oviparous fish to hormone treatments has been well discussed previously. Therefore, the present study was conducted to compare the sterilization due to 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 and 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 and 40 fish. The hormone was added to the food by the alcohol dry method. After the hormonal treatment period, the gonads of the fish were examined histologically. The results of present study showed that 300 MT hormone per kg of food caused in 97.6% of sterilized individuals in cichlid, which had a significant difference with other treatments (P<0.05). Also, 300 mg of the hormone per kg of food caused 37.7% of sterilized individuals in guppy, 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 hormones and the production of sterility. Also, the results showed that cichlid is more sensitivity to the hormone than a guppy. In conclusion, it can be argued that the oral treatment of MT causes sterilized populations, which can avoid early and undesirable breeding. As a result, reducing the fish culture period is useful in terms of time and economic efficiency for fish culture.