The experiment artificially gynogenetic fries of Carassius auratus auratus (redvariety) and the naturally gynogenetic ones of Carassius auratus gibelio, at the thirdday after hatching, were administered orally with methyltestosterone (MT) at fourdifferent concentrations: 25μg, 30μg, 50μg and 100μg per gram of diet. The dailyhormone diet, at about 7% as weight of the fry, was divided into two parts to feedat a. m. and p. m. This process was continued for 90 days and thereafter,the hormone-treated fry lived on a normal diet until they reached the stage at which sexingwas possible by laparotomy. The results of experiment were as follows: 1. the fries treated, with MT 25μg orMT-30μg hormone diet, developed into males except one having a gonad of ovotestis. 2.no males appeared by treating with MT-50μg or MT-100μg hormone diet. 3.60-84.6%gynogenetic fries of both kind of fish developed into males while they were daily fedwith the diet mixed with 95% crude alcohol (oneml per gram of diet) for a period of90 days. 4. the gynogenetic fry of the both sexes were fed with a normal diet onlythey all developed into females.