To create sex-reversed make tilapia, the eggs must be removed from the mother's mouth, incubated in hatching containers such as this, then fed commercial feed impregnated with methyl-testosterone for several weeks. This process leaves the genetically males still males and the genetically female fry now male as well. Male tilapia grow faster than females and, if there are only males in the pond, there is no spawning and the tilapia do not have to compete with their non-existent offspring.