The Mahi-Mahi (Coryphaena hippurus) is a striking pelagic fish known for its dazzling appearance in the open ocean. This fast-growing species is often incorrectly associated with the marine mammal dolphin due to its alternate name, dolphinfish, which is confusing but entirely different. It is also widely referred to by its Spanish name, Dorado, meaning “golden,” a nod to its brilliant coloration.
Overall Body Structure
The Mahi-Mahi possesses a body shape highly adapted for speed. Its structure is laterally compressed (thin from side to side), giving it a streamlined profile. This fish is a large species, commonly reaching lengths of about three feet, though exceptional individuals can grow to nearly six feet in length.
A defining characteristic is its single, long-based dorsal fin that runs almost the entire length of its back, starting near the head and ending just before the tail. The caudal fin, or tail, is sharply forked, a feature indicative of its ability to swim at high speeds in pursuit of prey.
Vibrant Coloration and Patterns
The living Mahi-Mahi displays spectacular, iridescent colors. The back and upper sides typically display brilliant, metallic hues of electric blue and vibrant green, reflecting light like a prism. This bright upper coloration transitions into a brilliant golden yellow on the lower flanks and belly.
The sides of the fish are often adorned with a pattern of scattered small spots that can be bright blue or black. These colors are controlled by specialized pigment cells called chromatophores, which can rapidly expand or contract. This dynamic coloration is a temporary spectacle, as the brilliant blues and greens quickly fade to a dull, muted yellow-gray shortly after the fish is removed from the water.
Distinguishing Males from Females
A distinct difference in head shape, known as sexual dimorphism, allows for easy visual separation between mature male and female Mahi-Mahi. The male, often called a “bull,” develops a very prominent, steep, and blunt forehead. This squared-off head profile is a bony ridge that becomes more pronounced and nearly vertical as the male matures.
In contrast, the female Mahi-Mahi, or “cow,” maintains a more rounded and gently sloping head profile. Her head tapers more smoothly from the dorsal fin down to the mouth, lacking the noticeable forehead protrusion seen in the male.