Ahi tuna: many people know tuna as ahi tuna. However, there isn’t a species named ahi. Ahi means ”tuna” in the Hawaiian language, so if you ask for Ahi tuna, all you are asking for is "tuna" tuna! Sometimes I like to just mess with people when they ask if I have ahi tuna: I ask what kind of tuna? "Ahi," they reply. "Yellow fin, big eye, or blue fin?" I ask. "No, Ahi!"
Most sushi bars carry three kinds of tuna; yellowfin, albacore, and big eye. The better sushi bars will also carry a fourth named blue fin. So next time you are dining out and you see ahi tuna on the menu, and you are feeling a little snobbish, ask what kind of ahi it is and see if they know… a good chef should know there is no such thing is Ahi tuna.