Tilapia breeding has now ranked second in the world's freshwater aquaculture industry. Since the growth of male and female individuals of tilapia is very different, farmers can obtain a single, fast-growing fish by artificially controlling the sex of the fish to speed up the growth of commercial fish, increase fish production, and increase economic efficiency. Work has been done in China for nearly twenty years. At present, the domestic method for producing single sex fish is: The South mainly uses purebred Olea tilapia males and purebred Nile tilapia females to produce full male Ouni fish. However, in the north, Nile tilapia is mainly induced by sex hormones, so that due to the influence of drugs, it can be converted into a single sex fish industry to increase fish production. The former is due to the introduction of several batches of Nile tilapia from different strains in the country, due to the genetic differences between different strains of Nile tilapia, and the differences in morphology are not very large. Therefore, at present, only a very small number of units in China have relatively pure native species of Nile tilapia. In addition, due to the fact that most of the units of tilapia are due to human factors and other factors, the males produced by Oni hybrid fish are not stable. The latter is not recommended due to artificial use of sex hormones to induce changes in the physiological characteristics of Nile tilapia, which will have more or less impact on the human environment and the body. In view of the current shortage of domestic male tilapia technology. We explore a new method that can increase the male rate without affecting the living environment and physical health of human beings. Insulin reversal individuals use the broodstock method to produce Onyx hybrid fish on a large scale. As early as the late 1970s, Changjiang Institute and other units have successfully tested this method, but there has been no report on large-scale production in China. We cooperated with the Guangdong Maoming Maonan Sangao High Breeding Breeding Base to use this technology to produce large-scale production of Onyx fry (about 1 cm). Through the results of the blood tests in 1996 and 1997, the male rate can be as high as 98%. We used the American purebred Nile tilapia (0.9-1.1 cm) provided by the Institute of Freshwater Fisheries Research Center (hereinafter referred to as “the Centerâ€) of the Maoming Sanhegao Breeding Base in Maoming, Guangdong Province (0.9-1.1 cm) for oral administration. The estradiol benzoate is continuously fed for 20-30 days (about 2 grams for every 10,000 fry), and the female conversion rate of Nile tilapia is about 95%, which is fed for another 3-4 months. It can be used as a broodstock to breed. Males that are clearly transformed and transformed from males of the purebred Olea tilapia have a male rate of more than 98%. In addition, at the same time, we also carried out a large-scale production of Onyx hybrid fish in the same way as the Maonan Three Gorges Breeding Base in Maoming, Guangdong, the Panyu Aquatic Technology Extension Station in Guangdong, and the Zhanjiang River Forces Fish Farm. And the purebred Oriya tilapia was provided by my "central" testing ground. The male test rates were 94-95%, 92-95% and 94-95%, respectively. We also used Methyl Testosterone to induce purebred Auricula aurantia at the breeding base of the Sannan High-quality Breeding Base in Maoming, Guangdong Province. After 3-4 months of breeding, the males and purebred American strains of the Nile were selected. In the tilapia hybrid production of Oni fish, the male generation rate of its offspring decreased by about 20%. Using this method, we must first pay attention to the purity of the parent of Nile tilapia and Oriya tilapia in order to ensure the male rate.