Alireza Khiabani - Department of Aquatic Science, Faculty of Agricultural and Natural Resource Sciences, University of Applied Science and Technology, Tehran, Iran
H Anvarifar - Department of Fisheries, Faculty of Animal Science and Fisheries, University of Agriculture and Natural Resources, Sari, Iran
H Mousavi-Sabet - Department of Fisheries, Faculty of Aquatic Science and Fisheries, University of Guilan

We examined the effect of ۱۷-α-methyltestosterone (MT) on the sex differentiation process in common platy (Xiphophorus maculatus). ۳–۵-day post-hatch larvae were fed different dose rates of synthetic androgen MT (i.e., ۲۵, ۵۰ and ۷۵ mg MT kg-۱) of feed and MT ۲۵, ۵۰ and ۷۵ mg kg-۱ plus ۱۰۰ mg kg-۱ Vitamin C (Vit C). MT and vitamin were administrated orally by using pellet dry starter and ethanol alcohol investigated for ۴۵ days. Survival and mortality rate were determined at the end of the experiment. The sex ratio was determined by secondary sex characteristics and macroscopic examination of the gonads after dissection. Univariate Analysis of Variance of masculinization was significant (P<۰.۰۵) however results of Duncan test showed that there is no significant difference among all experimental groups, in addition with intensification in MT dose, the masculinization was increased. Results of addition Vit C to treatments was significant (p<۰.۰۵) and results of Duncan test showed that there is significant difference among all experimental groups however in higher dose of MT survival was lower than low dose of MT. Vit C increased survival rate in groups ۲۵ and ۵۰ mg MT kg-۱. Nevertheless, the group ۷۵ mg MT kg-۱+Vit C had lower survival rate that this group without Vit C. The results of the present study showed that dose rate of ۷۵ mg MT kg-۱+Vit C caused maximum male population (۵۵.۹۶%) with ۱۷.۸۱% mortality, and dose rate of ۲۵ mg MT kg-۱ without Vit C caused minimum male population (۴۹.۴۷%) with ۱۲.۶۲% mortality. In conclusion results showed the doses of MT used in this study were not effective to masculinize the common platy fishes and Vit C was not able to increase survival in high dose of hormone. However, the use of steroid hormones has been banned and reduced, because they cause environmental and public health problems and are carcinogenic.

Common platy, Sex reversal, Poeciliidae