They like the temp around 75-78 degrees.

They can get along with somewhat large tank mates, but are likely to harass anything really small.

Absolutely not. The minimum recommended size tank for a lionfish is forty gallons, and that is pushing it. We sell these guys at work, and I find it amazing how many people don't think fish need to move!

I think there are some smaller species of lionfish that are relatively rare, but there might be one that could live comfortably in a twenty gallon aquarium.

(BTW: I didn't copy and paste from anywhere. ^_^ I researched them at work while I was looking into setting up a saltwater tank. *smiles*