The crocodile eel is a carnivorous fish that is extremely destructive and prefers to live alone, with a ferocious nature and a strong ability to survive, and is ranked as one of the world's top ten most ferocious freshwater fish. The crocodile eel lacks natural enemies in China, posing a great threat to indigenous fish and seriously jeopardizing the local ecosystem. The crocodile eel was introduced to China from the United States as an ornamental fish, and once it enters the aquatic ecosystem, it may have a serious impact on aquatic biodiversity and the ecological safety of the waters.

The adult giant bony tonguefish is up to 2-6 meters long, with a huge, long, slightly flattened body. The mouth is large and beardless, without mandibles, the tongue has strong and developed teeth, the swim bladder is rich in blood vessels around the inner surface of the honeycomb, often with special gill epiglottis. Scales are large and hard, inlaid, with rounded caudal fins, gray-green body, dark dorsal color, lighter abdomen, red caudal fins and posterior part of the body. It feeds on fish, shrimp and frogs and has great brute strength.