Just make sure the new fish arent the same size or color as the maroon. Gobys are fun. Jawfish you can do if you can get them food before the maroon eats it all. blennys, maybe some wrasses. I dont know if your tank is beg enough for tangs. it might be. You have lots of options, is the maroon the only fish in there right now? if it is, you might need to catch her, take her out, rearrange your rocks, add then new fish then add the maroon back in.