As the name suggests, it is a large eel, reaching up to 3 m (9.8 ft) in length and 30 kg (66 lb) in weight. Its serpentine in shape body has a brownish background color. While juveniles are tan in color with large black spots, adults have black specks that grade into leopard-like spots behind the head and a black area surrounding the gill opening.
Found in lagoon and seaward reefs. Commonly seen species along deep drop-offs and slopes in Indonesian waters. Benthic. Juveniles more secretive and occur on intertidal reef flats. It feeds primarily on fishes and occasionally on crustaceans. This is the largest Indo-Pacific moray eel, perhaps reaching 3 m in length. Because of its position at the top of the reef's food chain it is often ciguatoxic. Attacks humans when provoked.
The giant moray is carnivorous, it leaves its lair at night to actively hunt its prey along the reef. It mainly feeds on fish and occasionally on crustaceans. It is known to engage in cooperative hunting with the roving coralgrouper (Plectropomus pessuliferus).
Observations on prespawning behavior include a pair entwined around one another lying on the bottom of the reef area.
This species may be hazardous to people. Being at the top of the food chain, it is likely to cause ciguatera poisoning if eaten. It has been implicated in provoked and unprovoked attacks on scuba divers.