Green Moray might be easy to keep, but they can become quite large and they are predators so other fish can easily become food rather than prized specimens. The 29 gal smdfi mentions in his profile is certainly too small for a Green Moray.
Personally I don't consider eels to be fish, at least in any traditional sense. I think they are more like snakes. Definitely cool to have one, but they require special care in my opinion.
I don't mean to be contentious, just offering my view.