The guppy (Poecilia reticulata), also known as the millionfish or rainbow fish, [3] is a member of the family Poeciliidae and, akin to most New World members of the family, is considered a livebearer. [4] Male guppies, which are smaller than females, have ornamental caudal and dorsal fins. Wild guppies generally feed on a variety of food sources, including benthic algae and the larvae of aquatic insects. [5] Originating from northeast South America, it has been introduced to many ... How to prevent and deal with aggression in guppy communities? Aggression in guppy communities can be prevented and dealt with by following these tips: Maintain a proper sex ratio: The ideal sex ratio for guppies is one male for every two or three females . The Guppy is a small species of fish in the Poeciliidae family. People keep quite a few members of this family as aquarium fish, including the molly, swordtail, platy, and more. This species naturally lives in northern South America. However, people have introduced it outside of its native range across various regions of the globe. Read on to learn about the Guppy . Guppies are vibrant, easy-to-care-for fish from South America. Learn about their habitat, diet, and how to manage their breeding in your aquarium.