Ankoro

Ankoro is a gigantic anglerfish under the command of captain Vander Decken IX, residing in the Underworld of the Sea, seven thousands meters underneath the ocean surface. Wadatsumi seems to regard Ankoro as a pet, as apparently Ankoro has needed to be told to "not to eat ships" before.

Appearance
Ankoro is a giant grey-brown angler fish, with tiny white eyes, veiny fins, and a huge yellow light on the tip of its antennae.

Personality
When he was about to eat the Straw Hats' ship, he was stopped by Wadatsumi. Therefore, it seems Wadatsumi has a problem with Ankoro eating ships.

Abilities and Powers
He has a massive row of sharp teeth, so he is presumably ferocious and eats his prey.

History
It tried to eat the Straw Hat Pirates and their ship, the Thousand Sunny, but was stopped by Wadatsumi, who told him to stop eating ships.

Ankoro was later seen again when Vander Decken IX was talking to Wadatsumi about Shirahoshi. As of now, the fish's whereabouts are unknown.

Trivia

 * Its name comes from "ankō" (アンコウ), the Japanese word for anglerfish.