Mahi-mahi are swift and acrobatic game fish with striking colors. These colors darken when the fish dies (see illustrations) The current IGFA all tackle record is 88lb, caught in 1998 in Exuma, Bahamas by Chris Johnson of Lake Mary, Florida. Catches average 15 to 29 lbs, and any mahi-mahi over 40 lbs is exceptional. Males are often larger than females.
Mahi mahi are also known as dorado or dolphin fish. However, they are not at all related to dolphins. Dolphins are air-breathing mammals, whereas mahi mahi are water-breathing fish, distantly related to perch. They are similar in taste to flounder and other whitefish.
Mahi-mahi are a blue-water, open ocean, highly migratory schooling fish found around the world in tropical and subtropical waters at depths up to 279 ft, but more typically near 121 ft. They feed on forage fish, such as mackerel and squid, and also zooplankton and crustaceans. They are particularly adapted to hunting flying fish. They spawn in warm ocean currents throughout much of the year, and their young are often found among seaweed. They are a relatively short lived species, with a life span of only four or five years. Mahi-mahi are among the fastest growing fish, with a minimum population doubling time under 15 months. This makes them resilient to fishing pressure. However, their current vulnerability is moderate to high.
In earlier years, most mahi-mahi were caught accidentally, as bycatch in tuna and swordfish long line commercial fisheries. Now they are sought by both commercial and recreational fishermen.
A typical fishing technique is to take a sport fishing boat to the edge of a reef in about 120 feet of water and troll near a line of floating sargasso weed . Mahi-mahi often congregate around marine debris such as floating boards, palm trees and fronds, often found in association with such weed lines. Sargasso sometimes holds a complete ecosystem from microscopic creatures to seahorses, small crabs, juvenile triggerfish and other baitfish. Frigate birds dive for the food accompanying the debris or Sargasso. Other fish may be present in the area. Experienced fishermen can tell what species are likely around the debris by the birds’ behavior.