Lightfish

The Lightfish is an unplayable fish Animal Friend who appears in Donkey Kong 64 in the Gloomy Galleon level. He acts in the same way as Glimmer the Angler Fish, following the player around while lighting the way. He appears in the two sunken ships at the level, meaning that there might be two or that the two ships are connected somehow. The official site uses the wording "a Lightfish," suggesting that they're a species.

In his official artwork, he's purple and has a more anglerfish-like mouth.