Hi! When they are young, it's impossible to tell which sexs they are. When they get older the male is a bit smaller then the female. The male also has a different thumb. The tumb is thicker. When they want to mate, the male will make a soft almost barking sound. Females don't make a sound.
They will breed very easy, and they will lay eggs after a cold water change. You will have to keep the small ones away from the adults because the adults eat the small ones.

For the best breeding results you will have to keep them at low temperatures in winter. You can store them in a cool place in a plastic container with some hiding places.