Blue-Finned Elephant Tuna

A Blue-Finned Elephant Tuna(Titanic Tuna in the English anime and Elephant True Bluefin in the English manga) is a fish that comes from the South Blue and has elephant-like features. It is known as 'the jewel of the sea' it is supposed to be a miracle ingredient for cooking. It is not found in the East Blue.

In the original manga, Sanji bought one, while in the anime, Sanji competed in a contest against another cook, Carmen and won it.

During the Laboon arc, Sanji cooked and prepared the fish for everyone while they were talking to Crocus in Twin Cape. Usopp and Sanji were paying attention to Nami and Crocus's conversation while, unbeknownst to them, Luffy ate up the rest of the fish including the bones.

This enrages Sanji because he wanted Nami to have the "best of it" and kicks Luffy in the face.