The family Anguillidae, commonly known as eels, includes various species of elongated fish found in both freshwater and saltwater environments. They are characterized by their snake-like bodies and lack of pelvic fins. Eels are known for their unique life cycle, which often involves migrating between freshwater rivers and the ocean for breeding. Eels play an important role in aquatic ecosystems as both predators and prey. They primarily feed on small fish, crustaceans, and invertebrates. Some species, like the European eel and American eel, are notable for their long migrations to spawning grounds in the Sargasso Sea.