Bombfish

In Twilight Princess, the Bombfish (or Bomb Fish) is a blue, piranha-like fish found swimming around in the Lakebed Temple and hidden caves in Hyrule Field. The Clawshot can be used to drag one towards Link as well as arm it, allowing it to be used in a manner similar to a regular Water Bombs. If caught while fishing, the Bomb Fish can be kept as a Water Bomb. It does not have an entry in the journal, as it is "forbidden" to catch. The main use of a bomb fish is to blow open walls in the Lakebed Temple maze. Morpheel will release Bombfish from his mouth when Link is fighting him.