[2] Similar to other anguillids, the giant mottled eel is cylindrical with small, well-developed pectoral fins and a protruding lower jaw.

[2] It has also been found in other more distant regions such as the Galapagos possibly due to abnormal larval transport associated with El Niño-Southern Oscillation events.

[2] This species and all anguillid eels are catadromous, migrating sometimes long distances out into the open ocean to spawning over deep water.

[9] Marbled eels spend their adult lives in freshwater or estuarine habitats, and migrate to the ocean to reproduce.

[3] When the eggs hatch, the leptocephali drift in ocean currents for months until they reach estuaries as glass eels where they migrate upstream into freshwater as elvers.

[3] The marbled eel is carnivorous, but harmless, with a wide-ranging diet, eating shrimp, crabs, bony fish, and frogs.

[12] Large individuals of this species are also highly regarded and are not harmed by native people in some island groups of the western Pacific.