The story
From a name mistakenly assigned, Girardinus guppii, after biologist Robert J. L. Guppy, to previously assigned Poecilia reticulata.
Etymology from Wiktionary, CC BY-SA 4.0.
guppy
Today it means: A species of tiny freshwater fish, Poecilia reticulata, popular in home aquariums, that usually has a plain body and black or dark blue tail for the females and a more colorful tail for the males. The guppies can vary in size, but males are 4 cm (1.6”) and females are 7 cm (2.8”). Full definition →