Thunnus is a genus of ocean-dwelling fish in the family Scombridae, all of which are tuna, although other tuna species are found in other genera. The name of the genus is the Latinized form of the Greek ??????, th?nnos, tuna, the word being first mentioned in Homer. Due to overfishing the genus range has been significantly reduced, being effectively removed from the Black Sea, for example.

Their coloring, metallic blue on top and shimmering silver-white on the bottom, helps camouflage them from above and below.

They can grow to 15 feet long and weigh over 1,000 pounds. They can swim up to 50 miles per hour when pursuing prey.

The worldwide demand for sushi and sashimi, coupled with increasing population growth, has resulted in global stocks of the species being overfished and bluefin is the most endangered and considered "a serious conservation concern". Complicating the efforts for sustainable management of bluefin fish stocks within national exclusive economic zones (EEZ) is bluefin migrate long distances and hunt in the mid ocean that isn't part of any country's EEZ and therefore have been vulnerable to overfishing by multiple countries' fishing fleets. International agreements and conventions are good faith agreements and are difficult to monitor or enforce. Though this fish has been farmed in captivity by the Japanese and by the Australians with the help of the Japanese, yields are lower than other farmed fish due to the slow growth rate of Bluefin tuna, therefore keeping prices high.