This makes it very tasty

Tuna can swim for a very long time, so the muscles need a lot of oxygen. The reddish myoglobin in the muscle then serves to store oxygen, so most tuna meat has a reddish color. The flesh of other fish in the high seas - such as striped sharks and swordfish - are red-meat fish.

Tuna has red meat all around, but tuna have a strip of brown meat that extends from the head to the tail, on both sides of the body - this part of the meat is so fishy that it is often discarded.