Thanks for the reply Greg,
Can you explain a bit more your choice, and for which aray of fish.
My LFS suggested the dwarf fuzzy for the 40. This is what got me started...
LFS suggested Tomato Clown, Fuzzy Dwarf, Marine Betta, and Snowflake Eel, would be fine for bio load and tank size.
A. tomentosus stays on the smaller side and are very mild-mannered, so they fit in with a lion's disposition. I've kept them with lions and small waspfish and scorps, and they're always model citizens.
You've actually touched on a couple of fish that I have a negative opinion of (I've kept them myself, so it's been my experience).
I'm not really fond of clownfish...OK, that's putting it mildly. I refuse to keep any fish that gets so mean that you can't put your hand in the tank. They also get nasty with their tankmates once they get some size on them. Remember that clowns are just nasty little damsels in fancy pajamas.
If you want an eel, I'd look into a golden dwarf moray They max out at about a foot and have a better disposition than the SFE, which also get aggressive once they hit about 20" or so. The specimen I had for 15 years managed to bite me twice and kill more than a few tankmates.
Another "eel" option is the green wolf "eel"/"blenny", which is actually a member of the dottyback family. They also reach about a foot or so.
When you keep venomous fish, it's a good idea not to have to worry about other tankmates causing a commotion (with you or the other fish). That way, you can concentrate on where your lion is while working on the tank.
As for the 'nem, you'll need to light your tank accordingly, but a BTA (
E. quadricolor) is the best candidate for success.