a small, freshwater fish (Poecilia reticulata), a livebearer native to Barbados, Trinidad, and Venezuela: it is often kept in aquariums because of its brilliant coloring
See guppy in American Heritage Dictionary 4
(gŭpˈē)
nounpl.gup·pies
A small, brightly colored live-bearing freshwater fish (Poecilia reticulata or Lebistes reticulatus), native to northern South America and adjacent islands of the West Indies and popular in home aquariums.