The Blackfin Tuna is considered a small tuna, running around 10 pounds, but can get over 40 pounds. It is a marine fish that can reach up to 6 feet in length. The Blackfin Tuna is found in tropical and subtropical waters all over the world, including the Atlantic Ocean, Pacific Ocean, Indian Ocean, and even some parts of the Arctic Ocean. The Blackfin Tuna has a slim shape and sleek body with a dark blue back that fades into a silvery color on its stomach area. It has small scales on its head and tail area which gives it more surface area for catching prey such as small fish or crustaceans. The Blackfin Tuna can be found near reefs or open waters where there is an abundance of food sources such as mackerels or herrings; however they are also known to eat squid or octopus if they are available.

In terms of temperament, the Blackfin Tuna is generally considered aggressive towards other fish species but not necessarily humans unless they feel threatened by them (i.e., being caught by fishermen).