From the Super Mario Wiki
Glad Blooper is a Blooper enemy found on Vibe Island in the game, Super Princess Peach. It is just like a regular Blooper, but it has been effected by the Vibe Scepter. It only appears in some underwater sections in the game in Wavy Beach and Gleam Glacier. It swims in figure eights.
According to the game's Glossary, Glad Blooper is "A laid-back enemy that swims happily in the water."