Eels are an iconic and often mysterious species of fish. Eels have a long, slender body and are found in both fresh and saltwater. Eels can range in size from a few inches to several feet long, depending on the species. Some species of freshwater eels, such as the Fire Eel, are actually elongated fish and not true eels. There are over 1000 known species of eels between freshwater and saltwater, belonging to 20 different families and 8 suborders of the order Anguilliformes. Eels are an important species in many aquatic ecosystems and are a popular species and aquarists.