Black Marlin

Quick Take

• The black marlin's reputation as one of the ocean's fastest swimmers hides a scientific reality that contradicts popular belief. See the speed reality →
• This fish is technically edible, though it's banned in parts of the world for a reason most diners would never guess. Find out why it's banned →
• Male and female black marlins live dramatically different lifespans, and the cause reveals something counterintuitive about the species. Explore the lifespan gap →
• One physical quirk makes the black marlin instantly distinguishable from every other marlin, though it only appears under a very specific condition. Spot the unique physical quirk →

Usually found in the Indian and the Pacific oceans, the black marlin is a fish that comfortably exists in the tropical and subtropical areas and can swim at burst speeds of around 36 kilometers per hour, though popular claims of up to 80 miles per hour have been disputed by scientific evidence. It is a species of marlin and has a maximum length of 15.3 feet. These marine creatures can reach a maximum weight of around 1,650 pounds, and they belong to the family Istiophoridae, which also includes sailfish. The sailfish is considered the fastest fish in the world.

5 Incredible Black Marlin Facts

Classification and Scientific Name

Black marlins go by the scientific name Istiompax indica and belong to the family Istiophoridae, and are closely related to sailfish. They come from the class Actinopterygii and order Istiophoriformes. The genus is Istiompax. Meanwhile, the kingdom is Animalia, and the phylum is Chordata.

With a close relation to the swordfish, the black marlin is one of several different types of marlins. The word “indica” in their scientific name is Latin for “of India.”

Appearance

Black marlins are marine animals that have a shorter bill. Their dorsal fins are lower, and they also have a lower, more rounded dorsal tip. These fish can be easily differentiated from other marlin species since they have rigid pectoral fins, which become noticeably fixed especially in fish weighing around 150 pounds.

Their pectoral fins lie flat against their bodies, and they have between 39 and 50 dorsal rays. They are usually about 183 inches long and weigh around 1,653 pounds.

Distribution, Population, and Habitat

Black marlins are usually found in shallow waters. They exist close to continents, coral reefs, and islands, and swim around depths of zero to 500 meters. However, most of them rarely go below 30 meters. They are found in both tropical and subtropical waters of the Indian Ocean as well as the Pacific Ocean, and can occasionally also enter temperate waters.

Although the exact population is unknown, black marlins have not yet been declared threatened or endangered.

Predators and Prey

Black marlins usually feed on squid, cuttlefish, octopods, fish, and large crustaceans. As these fish go after their prey, some research suggests they attack with a fast slash of their bill, similar to the hunting technique of the swordfish. The only time that these fish go after tuna is when the waters that they are in have them in abundance.

The only significant threat to these fish is humans, who hunt them for sale or as trophies. Even though they tend to have high mercury levels, they are still fished for food.

Reproduction and Lifespan

Black marlins reproduce by external spawning. They release eggs into warm waters; the eggs later hatch into juvenile fish that grow rapidly. A female can carry up to 40 million eggs, which hatch after a short incubation period.

Females are known to live up to 13 years, while males live only about 7 years. This difference in lifespan is attributed to sex-specific mortality rates in this species.

Black Marlin in Fishing and Cooking

This fish can be caught and cooked. However, despite being edible, it has been banned in some parts of the world because its flesh contains high levels of selenium and mercury. In fact, many chefs recommend against consuming this fish, and it is considered one of the top fish to avoid consuming.