The Guppy fish is probably the most popular aquarium fish species in the world, also one of the cheapest fish in shops. Small, beautiful, peaceful, lively, curious and hardy, there are many colorful variations Guppies are live-bearers. The fry can left for themselves immediately after they are born. As a matter of fact, the guppy fry are a delicacy to most fish. Guppy babies are often eaten by adult specimens.