Actually...here is a much bigger list:
http://www.nano-reef.com/forums/inde...howtopic=74703
They do list Flame Angels on the 20g list, but they also have Maroon Clowns on the 20g list...so take it with a grain of salt that's for sure!!!
I'm just trying to give you other options. It's a pain in the butt to capture fish out of a tank, not to mention stressful on the fish. In the end it's your call. They are nice looking fish.