bluefin tuna

[bloo-fin] /ˈbluˌfɪn/
noun
1.
a large tuna, Thunnus thynnus, common in temperate seas.
Origin
1920-25; blue + fin
British Dictionary definitions for bluefin tuna

bluefin

/ˈbluːˌfɪn/
noun
1.
another name for tunny