I would say that a pair of clowns would be good. Beware that you aren't able to put many fish in such a small tank. I have two damsels in my 30 gallon. Pretty little buggers, but VERY mean and territorial. All mine do is hide...so I wouldn't recommend damsels. You could also put a goby or blenny and maybe some clowns. You could put at most four fish...and that's even pushing it. But that's just my personal opinion. I believe in presenting the most docile environment possible. I for example, have a pair of percula clowns, a pearly headed jawfish, and a cinnamon clown in the same 55 gallon tank. Most would say not to mix clown species, but they all get along and I believe it's a reflection of the tank size and lack of overcrowding. A lot also depends on the personality of the fish. My percula clowns get along with everyone, but my cinnamon clown is relatively territorial. Each fish basically minds it's own business though, oblivious to the others. When you add an anemone into the mix, however, clowns heighten their territorial demeanor. Just remember to avoid overcrowding. Note that you also can't put fish that grow large, such as angels, tangs, triggers...a lot of fish let's just say. But don't get me wrong...the small fish sometimes tend to have the most interesting personalities. I have a pearly headed jawfish (yellow-headed jawfish) and he is the cutest thing. He is constantly burrowing and maintaining his little home under the live rock. He has a network of tunnels and it's amusing to watch him dig the tunnels, go in one hole and come out another. Also beware that smaller tanks tend to warrant higher upkeep as they reach toxic levels quickly and dirty more rapidly considering their size. You can have inverts, such as blue-leg hermits...but also beware that many inverts may become territoral considering the amount of space in the tank. It's just a test of achieving the best ratio of livestock to tank space. Good luck!
[ June 14, 2001: Message edited by: misty927 ]