From the Super Mario Wiki
Loch Nestor is a puffer fish enemy encountered in Super Mario World 2: Yoshi's Island, its remake Yoshi's Island: Super Mario Advance 3, and Yoshi's New Island. It only appears in stages where Yoshi must morph into a submarine. It's the underwater counterpart of Boo Balloon, but whereas the Boo always chases the player, Loch Nestor merely retaliates if struck first. If it is hit by a torpedo, it simply grows two times larger and chases Yoshi. After it is hit three times, it explodes.
Loch Nestor derives its name from Nestor, a given name, and the Scottish lake Loch Ness, which is the home of the legendary Loch Ness Monster.
Names in other languages