The guppy, also known as the millionfish, is one of the most popular freshwater aquarium fish species in the world. It is a small member of the Poecilidae family (females 4–6 centimetres long, males 2½–3½ centimetres long) and like all other members of the family, is live-bearing. Taxonomy Robert John Lechmere Guppy discovered this tiny fish in Trinidad in 1866, and the fish was named Girardinus guppii in his honour by Albert C. L. G. Gunther later that year. However, the… (More on Guppy)