Ku

Kus, previously known as Zora's Spawn (shared with Zoras) and Dark Zoras, are a cycloptic -like creature that acts similar to enemy Zoras, spitting fireballs from the water.

The Legend of Zelda: A Link to Past
In The Legend of Zelda: A Link to Past, Dark Zoras appear in various bodies of water across the Dark World, such as the Ice Lake and Swamp of Evil. They act like normal Zoras do in deep water, but are stronger.

While Dark Zoras do not appear in shallows like normal Zoras do, a misplaced spawning point for one exists in the Swamp of Evil. Due to there not being any associated programming for a land-based Dark Zora, it does not appear, but its death effect can be seen if Link uses a Medallion near it, and certain other items collide with it.

The Legend of Zelda: A Link Between Worlds
In The Legend of Zelda: A Link Between Worlds, Kus appear in Lorule's bodies of water. Most act the same as before, but some at the Lake of Ill Omen and the Treacherous Tower walk on land to quickly pursue Link, showing them to have turtle-like shells.