More than one damsel/30 gal.

[canadawest]

Damsels in the Chromis family would probably be your only safe bet, and even then a 30gal is pushing the comfort envelope for such territorial fish.

I have a Yellow-Tailed Blue Damsel in my 100gal, but he is the only damsel in the tank. Never has bothered any other fish at all and is one of the longest tenants in my tank (about 18 months).

I don't think I would try adding more though, even though I seem to have a fairly docile one.

Why not try a small group of green or blue chromis? 3-4 small ones would probably get along fine in a 30gal.