As with all tunas, members of this genus are warm-blooded, which is a rare trait among fish; this enables them to tolerate cold waters and to dive to deeper depths.

[3] Bluefin tunas, for example, are found in Newfoundland and Iceland, and also in the tropical waters of the Gulf of Mexico and the Mediterranean Sea, where some individuals go each year to spawn.

[4] The word Thunnus is the Middle Latin form of the Greek thýnnos (θύννος, "tuna, tunny") – which is in turn derived from thynō (θύνω, "to rush; to dart").

However this classification has been questioned by a recent phylogenetic analysis of nuclear DNA sequence data, which resolved different relationships among species and did not support the traditional definition of the bluefin and yellowfin groups.

[11][12] The worldwide demand for sushi and sashimi, coupled with increasing population growth, has resulted in global stocks of the species being overfished[29] and bluefin is the most endangered and considered "a serious conservation concern".