If you buy a supermale, you can breed it to normal females and raise these fry at 70F for 30 days. Any females that appear will be genetically male. Breed these back to the supermale and 50% of the offspring will be supermales. Raise these at 70F for 30 days and some of these will be genetically supermale, but female. Breeding these with the supermale will give supermale offspring.

This takes a long time and requires lots of tanks. The sex of young fish can be checked via a process called gonad squash, but this involves killing the fish, removing their gonads, and checking them under a microscope. This only determines if they are a physical female or a physical male.

It is a lot less trouble just to raise your fry at 96F for the 1st 30 days. This will give you about 95% males. There are a number of papers on this.