Latin name

Anguilla marmorata

Other name

Marbled eel

Identification

The giant mottled eel is cylindrical in shape with small, well-developed pectoral fins and a protruding lower jaw. It has thick, fleshy lips and small oval scales that grow into the skin. The head is rounded and the snout is depressed. The teeth are small and arranged in bands. It has a total of 100 to 110 vertebrae. It is distinguished from all other species by its mottled coloration and long dorsal fin, which begins closer to the gill opening than the anus.

Features of fish fins

This species has dorsal and anal fins that end around the tail, and the dorsal fin begins between the pectoral fins and the anus. There are no pelvic fins.

Fish colouring

Unlike some other eel species, the giant mottled eel is mottled in coloration. Adult eels are yellow with greenish brown or black marbling on the back and white on the abdomen. Juvenile eels are less marbled and grayish to yellow in color. 

Distribution

This species is found from East Africa to French Polynesia and north to southern Japan. In Africa, it is found in Mozambique and the lower Zambezi River. The giant mottled eel has the widest distribution of all Anguilla eels. It has also been found in other more remote regions such as the Galapagos Islands, possible due to anomalous larval transport associated with El Niño Southern Oscillation phenomena. Anguilla marmorata is not listed on the IUCN Red List of Threatened Species, but it is endangered in Taiwan.

Habitat

Marine freshwater brackish bottom species. Depth ranges from 0 to 3000 m. Typically found in tropical climates between 24°N and 33°S. 

Size

The female can grow to 2 meters, the male to 1.5 meters and weigh up to 20.5 kilograms, making it the largest species of Anguilla eel. The giant mottled eel can live to be about 40 years old.

Behavior

They are nocturnal, meaning they are active at night. Adults of this species inhabit the bottom of fresh and brackish waters, rivers, lakes, and tributaries. As a catadromous species, they sometimes migrate long distances into the open ocean to spawn in deep water. The spawning area is known to be west of the Mariana Islands in the northern equatorial current in the western North Pacific, but other spawning areas are thought to exist in the western South Pacific and the Indian Ocean.

Food and feeding habits

Carnivorous but harmless, their diet is varied, including shrimp, crabs, bony fish and frogs. 

Reproduction

While in the river, the sex glands do not develop. But in winter, as they move from the creek to the mouth of the river, the sex glands begin to develop as mature individuals go to the depths of the sea to reproduce.

Fishing

There is a commercial fishery for this species.

Relationship with a person

Harmless. Used as a food source in some areas. Large individuals of this species are highly prized by the indigenous people of some island groups in the western Pacific and are not harmed.