What methods are there for controlling the sex of fish?

Controlling the sex of fish is an effective way to increase fish production. Generally, sex hormones can be used to induce the sex of fish to develop in the direction people want. Sex hormones are divided into two types: those secreted by the testes are male hormones, and those secreted by the ovaries are female hormones. The primitive germinal epithelium tissue of fish simultaneously has two components: the cortex, which determines development toward female, and the medulla, which determines development toward male. Under the action of female hormones, the cortex differentiates into ovaries, while the medulla does not develop, resulting in a female with egg-laying reproductive function; conversely, under the action of male hormones, the fish will become male. Therefore, in the process of developing fishery production, if one wants to increase the number of female carp, crucian carp and other fish, female hormones can be used for treatment, that is, when the fry in the fry pond begin to feed, a certain amount of estradiol benzoate is added to the feed, and with continuous treatment for 2 to 3 months, the proportion of females can reach about 95%. Similarly, using the male hormone methyltestosterone to treat tilapia, @#@236@#@ and other fry can yield more than 99% male fish. Because the treated fish have a single sex and a fixed density, they not only grow quickly but also have low costs, and generally can increase production by about 30%.