I think you should just get a cute little coral beauty. He will eat caulerpa, but, oh well, the fish is way better than the plant, IMO. I don't think there are any dwarf angels or tangs that won't eat caulerpa. Except maybe a resplendent angel...but it would cost THOUSANDS to get one. I really love coral beauties, and plan to get one once I buy and cycle my 55 in a couple months. It's the only fish that's absolutely essential for me to have besides a clown. I think a percula will be my choice.