The guppy (Poecilia reticulata), is a species of freshwater aquarium fish. It is one of the most popular aquarium fish species. The guppy is also called the millionfish. It is a small member of the Poeciliidae family (females 4–6 centimeters (1.6–2.4 in) long, males 2.5–3.5 centimeters (1.0–1.4 in) long). Like all other members of the family, it is live-bearing. Guppies are popular aquarium kept fish because of their inexpensive needs and beautiful color ranges.