Skullfish

Skullfish are skeletal fish enemies which prowl the waters of Majora's Mask and Twilight Princess.

Majora's Mask
Skullfish live in the seas around Great Bay in Majora's Mask. They spawn at certain intervals within the bay and swim towards Link, biting him if he does not raise his defenses. Zora's Link's electrical attack makes quick work of these pests.

Twilight Princess
In Twilight Princess, Skullfish appear in the Lakebed Temple, as well as in another cavern in Hyrule Field. They can be caught with the Fishing Rod, and will even drop a Recovery Heart when released, although they are illegal fish and will not be recorded in the fish journal.