If you want to replace the coral beauty with another angelfish, WetWebMedia says the dwarf pygmy angels (Centropyge argi, Centropyge acanthops and Centropyge aurantonotus) can do well in smaller tanks. However, that being said, I have an African Pygmy (Centropyge acanthops) in my 29 and at times the tank seems a bit small for it. I may be wrong and defer to more advanced aquarist, but I thing just about any angelfish dwarf or otherwise is a 50/50 proposition as far as picking at corals goes. So far so good with mine, but you never know.
If you're just looking for a fish that will do good in the 29 gallon tank, a goby or something like a purple (Nemateleotris decora) or helfrich's ( Nemateleotris helfrichi) firefish can add a lot of color and personality. If you decide on a firefish be forewarned they are for peaceful tanks only. While at the fish store waiting out the two week "make sure it lives" period, my purple firefish accedentially got put into a holding tank with a psuedochromis and had most of the purple/orange fin down his back and tail eaten off and was cowering in the corner behind a rock when we found him and put him back in the correct tank.
PS firefish are jumpers and will need a good covering over the tank.
