Genus-Animalia: Coryphaena

Coryphaena is a genus of marine ray-finned fishes known as the dolphinfishes. This genus is currently the only known genus in its family. The species in this genus have compressed heads and single dorsal fins that run the entire length of the fishes' bodies. Dolphinfishes are some of the fastest-growing species in the ocean, so serve as a primary food source for many pelagic predators. The dolphinfish can reach up to about 40 kilograms (88 lb).

Dolphinfishes are unrelated to dolphins (which are mammals), and commercially their meat is often labeled with its Hawaiian name mahi-mahi to reduce possible public confusion. The origin of the name "dolphinfish" is recent, to avoid confusion with dolphins, as the traditional name of the fish was also dolphin. Why the mammal and the fish were both called dolphin is uncertain, but theories include that dolphinfish communicate using high-pitched sounds similar to a dolphin, because they are about the size of a small dolphin, or due to dorado (Spanish for "golden") having been purportedly used historically in Spanish for both dolphins (normally delfín) and dolphinfish.

Reference: Wikipedia