Hi...the Flame Angel is not really considered a good 'nano' fish. Some may be able to make it work, but:
1) they can be aggressive towards other fish
2) there is no guarantee that they are reef safe, ie, may nip at your corals
3) most importantly, they can reach 4 inches, that is large for a fish in a nano tank and, the possibility of overloading your system is a possibility unless it is alone or one other fish
I'm not saying that you can't do this nor that it couldn't work. But..in general..if you truly want to build a SAFE nano reef, not risk your livestock and corals, then this fish is not on the list of ones to consider. If you want one, make sure it is the last fish you add to your tank....the most aggressive species should go in last. Just MO. SH