I breed Tiger Barbs. Yes the females belly will be much bigger. The males will have red noses and red tips on there fins when they are mature. If your interested in breeding them you have to pick out one pair. Put this pair in a 10gal. divided tank for a few days so they can see each other. Put the decorative marbles on the bottom of the
bare bottom floor tank. Then release them together.This way the fish can't get at and eat the eggs. The male will chase the female around. When she is ready she will let him rib against her. They can keep up for a full day. You'll know they are done when they each goes to there oown corners and ignore each other.