They like to burry themslelves in the gravel. You also have to make sure that you have a well covered aquarium.
They are preditors, they need a varied diet including earth worms, blood worms black worms, carnivor pellets ect.
Water temp should be around 72 to 82 degrees, they can benifit from a little salt in the tank. You also shouldn't have any small fish (that you are attached to) that the eel can fit in his mouth.