Bubba

Bubbas are big pink or orange fish (usually wearing sunglasses) that will eat Mario if he gets too near them after a while. They look and act very similar to Boss Bass from Super Mario Bros. 3. Bubba appears to be a species of Blurp. Related to them is the small Bub fish.

Super Mario 64
Two Bubbas appear in Tiny-Huge Island and they cannot be defeated similar to most aquatic enemies in Super Mario 64. If Mario is eaten, he will lose a life, regardless of his current health. In Super Mario 64 DS, they are replaced by Big Berthas.

Mario Party
Additionally, stepping on a Happening Space on Yoshi's Tropical Island, a gameboard in Mario Party, Bubba would eat Toad, switching Toad's and Bowser's position.

Mario Golf
In Mario Golf for the Nintendo 64, either a Bubba or Blurp will eat the ball if it lands in the water. They are also much smaller in this game.

Trivia

 * The Cheep-Cheeps from Super Mario Sunshine are often confused as Bubbas, but they do not wear sunglasses and are smaller in size.