Triodon macropterus (common name the threetooth puffer and the black-spot keeled pufferfish) is a tetraodontiform fish, the only living species in the genus Triodon and family Triodontidae. Other members of the family are known from fossils stretching back to the Eocene. The threetooth puffer was first scientifically described by René Lesson in 1831 and is recognizable for its large belly flap which has the ability to blend into the body when fully retracted.