Guppies

noun

1. A 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.

   "Fred kept a tank of guppies by the windowsill."

2. By extension, any tiny fish.
3. A tube holding paintballs before they are loaded into the gun.

   "2001, John R. Little, Curtis Wong, Ultimate Paintball Field Guide (page 177)"