The name “Dolphin Fish” often causes immediate confusion, as this marine creature is a fish species and not related to the aquatic mammal dolphin at all. Known scientifically as Coryphaena hippurus, this animal is more commonly referred to as Mahi-Mahi (Hawaiian) or Dorado (Spanish for “golden”). The fish is recognized for its brilliant colors and distinct shape, making it a highly prized catch for commercial and sport fishermen.
Defining Physical Structure
The Dolphin Fish possesses a sleek, compressed body designed for speed, allowing it to move rapidly through the open ocean. Its body is long and slender, tapering significantly toward a deeply forked, or lunate, caudal fin, which propels the fish efficiently through the water. Most adults commonly measure around 3 feet in length and weigh between 15 and 30 pounds, though they can reach lengths of up to six feet and exceed 50 pounds.
A particularly distinctive feature is the single, elongated dorsal fin that extends nearly the entire length of the fish, starting from just above the head and ending near the tail. This long fin, along with a similarly concave anal fin, contributes to the species’ streamlined profile. The mouth is large and contains numerous small, sharp teeth, reflecting its predatory nature as a fast-swimming hunter.
The Signature Coloration and Rapid Color Changes
The live Dolphin Fish displays one of the most spectacular and dynamic color patterns found in the marine environment. Its sides are typically a brilliant golden-yellow, which contrasts sharply with an iridescent back that shimmers with bright blue and green hues. Scattered across the head and body are small, metallic blue or dark spots.
This vibrant coloration is not static; the fish can change its colors rapidly in response to its environment or emotional state. When a Mahi-Mahi is excited, stressed, or actively feeding, its colors “light up,” becoming intensely bright and shifting with shimmering waves across its skin. This phenomenon is made possible by specialized pigment-containing cells called chromatophores, which are controlled by the fish’s nervous system.
The dramatic color change is most noticeable after the fish is caught. Upon death, the brilliant blues and greens quickly fade, and the fish’s appearance transitions to a dull, muted yellow-gray color. This swift loss of iridescence is a direct result of the chromatophores ceasing to function once the nervous system is no longer active.
Distinguishing Males and Females Visually
The most reliable visual difference between male and female Dolphin Fish is the shape of the head, a characteristic known as sexual dimorphism. Males, often called “bulls,” develop a very steep, almost vertical forehead profile as they mature. This results in a prominent, blunt, bony crest that gives the head a squared-off, block-like appearance above the eyes.
In contrast, the females, referred to as “cows,” maintain a more rounded and gently sloping head contour throughout their lives. The female’s head remains streamlined and tapered, lacking the prominent bony crest seen in the mature male.