For freshwater, get a Mastacembelid (Spiny Eels) or, if you can, a Synbranchid (Swamp Eels, they are illegal in many states, but can breath air, are very hardy, and eat very well). Avoid Muraenids (Morays), as there are only a few species that can survive in fresh water, and these are only for extremely advanced aquarists and really belong in brackish water anyway. Even in brackish water they are expert fishes. I currently have a Gymnothorax tile and an Echidna rhodochilus. The Florida Eel is commonly called the American Eel, Anguilla rostra, and can reach five feet in length. There are other eels I have seen called the Florida Eel, such as the Asian Swamp Eel, a Synbrachid introduced to Florida that may become an ecological problem for that state.
With luck, my Aquarium Morays website will be up and running soon, and there will be a large section on other aquarium eels.
