Vampire Fish

According to the Croc 1 GBC manual, the Vampire Fish is "A mean fish that snaps his jaws at Croc, be careful of his very sharp teeth!"

In Original Game
These fish appear a couple times in underwater stages of the original game. They are recognizable by their green bodies and red eyes. They swim in predetermined routes, but if Croc gets too close, they will attempt to bite him.

In GBC
These creatures do not chase Croc; rather they act as obstacles, swimming back and forth. Croc will take damage if he touches one.

Trivia

 * The sound effect for the Vampire Fish's bite in the original game is the same sound effect used in Croc 2 for Venus Fly Von-Trappe's bite.