Mahi Mahi - Dolphinfish Considered by many to be the most beautiful fish in the sea, the dolphinfish sports iridescent body colors—metallic blues and greens on the back and sides, with white and yellow underneath. Many dolphinfish have blue, green and/or black spots. A dolphinfish’s body is sleek and long, with a dorsal fin that extends from head to tail. A mature male’s forehead is high and sloping; a mature female’s forehead is less steep. That lunate (forked) tail propels this fast-swimming fish to speeds of 40 miles an hour. Dolphinfish is a popular menu item. To distinguish it from dolphins (which are mammals), restaurants have popularized its Hawaiian name—mahi mahi. Cool Facts: Dolphinfish live in the “fast lane.” They mature in four to five months, grow up to one-and-a-half feet per year and live a maximum of five years. Juvenile dolphinfish as well as several other species of pelagic fish are attracted to floating kelp mats, boats, sargassum, logs and debris. Since the floating objects don't provide food or much protection, scientists aren't sure why.