One of the very best signs of a healthy aquarium is fish which are ready to breed. It is many aquarists' dream to successfully breed fish at home. Though fish reproduce in a number of different ways there are several basic things you can do which will universally improve their chances.
It may sound obvious, but before you can breed your fish you will need at least one male and one female.
Determining the sex of individual fish is not always easy (the general rule is that female genitals protrude a little out of the body, in a small round bump, whilst male ones don't). Sex markings vary by species and with some species there is very little visible difference, so you'll have to make your decisions based on how the fish behave.
Observing behaviour is essential to successful breeding anyway, because most fish don't want to breed with just any other fish. They can be quite picky, and will be disinterested or even aggressive towards unsuitable individuals. Signs that fish are compatible can include frequent close physical contact, non-aggressive chasing (without biting but with some nudging of the belly) and possessiveness (driving away other fish who attempt social contact).Read more »