Sapi

Sapi was the fish salesman who sold Sanji the blue-finned elephant tuna which he claimed to have caught himself.

Appearance
He is half fishman and half human. He has a small ponytail that resembles a fish fin.

History
In the manga, he met Sanji and just sold him the fish. While in the anime, he told him about a competition that had the blue-finned elephant tuna as a prize.

Anime and Manga differences
In the anime, his name is Ness.

Trivia

 * He is currently the only known person to be a cross species of a fishman and a human.