The Nipple Fish is known as the nipple fish for two reasons, namely for attacking and latching onto the nipples of nearby mammals that enter the water and for the pink "nipple-esque" color of their underbellies.
"Tom was drowned by a group of Nipple Fish. Be careful, if you see a piranha, you better hope its a red bellied piranha. They'll just kill you.
Pink bellies- now they'll take you down slow. Starting with the nipples."