Any of about 100 species of marine eels (family Congridae) with no scales, a large head, large gill slits, a wide mouth, and strong teeth. Conger eels are usually grayish to blackish, with a paler belly and black-edged fins. Found in all oceans, sometimes in deep water, they may grow about 6 ft (1.8 m) long. Conger eels are carnivores. Many species, such as the European conger (Conger conger), are valued as food. The American conger, or sea eel (C. oceanicus), is a fierce game fish.