/gup"ee/ , n. , pl. guppies .
a small, freshwater topminnow, Poecilia reticulata, often kept in aquariums. Also called rainbow fish .
[ named after R.J.L. Guppy (1836-1916) of Trinidad, who presented specimens to the British Museum; catalogued under the NL name Gerardinus guppyi in 1866 ]