Tropical fish are generally classified as either "live-bearers" or "egg layers." Of these two, the live-bearers are usually much simpler to breed and raise. This is because the live-bearing fry is born fully developed and is usually larger than the egg-laying fry. The new fry can swim vigorously and can eat the same food finely chopped up as is eaten by their parents.

The live-bearers are easily distinguished as to sex, since the males have a modified anal fin with which to impregnate the female as he swims alongside her. You can easily recognize a pregnant live-bearing fish by her size and the dark area in the anal region behind the lower fin. Many human parents have found the reproduction of live-bearing fish to be a natural medium for educating their children concerning the "facts of life."

Since the live-bearing female and others are inclined to eat the little fry, you will want to supply protection for the newborn fish. The best way is to separate the mother from the other cannibalistic fish before she gives birth. You can then either provide the young with hiding places such as plant thickets or use some type of breeding trap to prevent the mother from getting at her babies.

Most tropical fish reproduce by laying eggs, and they employ a variety of methods to accomplish this. Some scatter their eggs over sand or gravel. Others fasten their eggs on plants or stones. Some egg layers will build nests, afterward guarding their young from predators. Many species of egg layers need specific breeding conditions, and sometimes special food. Thus more extensive knowledge is needed for successful breeding.

 When breeding tropical fish you need to be very aware of numbers the fish can have 20-30 babies.

The main concern is that the fish become inbred because the babies are mating and having babies there babies are having babies and so on and so forth.However, the fish will become abnormal,no major abnormalities just the fish wont be as pretty, will be a little bit longer, have a bent body, not live as long. if you want to prevent this then after breeding once or twice get rid of all the male or all the female fish so they cannot carry on the circle until you are ready to bread again.