The Giant mottled eel can be found in rivers and ponds around Mauritius and are a native species. They have a wide geographic range across the Indo-Pacific region and are present in the East Coast of Africa, across the Indian Ocean and the Pacific ocean as far as French Polynesia.
They are among the largest of the anguillid eels. Like other eels in the anguillid family, they are cylindrical, have well developed pectoral fins, a projecting lower jaw and fleshy lips with minute teeth. Their dorsal fin stretches from the back to the tail. Their scales are embedded in their skin in a basket weave pattern. They are thought to have between 100 and 110 vertebrae, reaching up to 2 meters in length for males and 1.5 meters for females. Their colour, as their common name suggests can be yellowish to olive or brown, mottled with dark greenish brown and lighter coloration below. It is thought that the giant mottled eel can live up to 40 years.
They can be found in freshwater, brackish and saline environments depending on their stages of life. Juveniles bear a yellowish colour and are more likely found for two to three years in warm productive habitats, while mature individuals may migrate to more northerly latitudes. Once they reach sexual maturity, these eels migrate to deep oligotrophic sea regions and spawn at depths between 150 to 300 meters. The geographic presence of eels at their different growth stages thus depends on coastal currents and gyre. The larvae spend about 114-132 days drifting with the plankton before recruiting to river mouths, at which stage they will move upstream and metamorphose into yellow eels. As they mature, in between 8 and 20 years, they become silver, before going back to the ocean to reproduce. This mottled eel prefers upstream freshwater habitats with running clear water, or the mid part of rivers avoiding high and low altitudes. Their choice of habitat may be affected by the presence of other eel species or pollution. The mottled eel is carnivorous eating shrimp, crabs, fish and frogs. It is a nocturnal animal.
Although listed as Least Concern, the mottled eel is of high commercial value, being fished, farmed and traded for consumption. Their skins can be used for leather products and accessories.
The giant mottled eel is amongst the largest species of eel on the planet.