Eels are one of the more fascinating species of fish in the aquarium trade. They are characterized by their long bodies and snake-like heads. Like catfish, most species of eels do not have scales. Their bodies are covered instead in soft, mucus covered skins. Eels are also unique in that they do not have separated dorsal and pelvic fins. Instead, their fins merge together with their tails to form a continuous fin ridge along their bodies.
While a relatively hardy species of fish able to survive in a wide array of aquarium conditions, eels aren’t recommended for beginner aquarists. For one, most species of aquarium eels can grow over 3 feet in length and require extremely large aquariums or outdoor ponds.