[Moogled]

I keep a Regal Tang in my 33 gallon. He's about 1.75 inches and does well in it.

Alot of people tell you that "it's ultimately your decision" but try to persuade you anyway. You can try for Bangaii Cardinals, they are uber-cool fish but you'll need to train them to eat pellets. If you really want a tang, a small (but not very young juvies, their mortality rate is higher) you can try something like a blue/yellow/tomini tang. Just be forewarned: tangs are aggressive fish that will compete for algae food source in a tank as small as yours so fish like Lawnmower Blennies won't be good tankmates.

My opinion? Try it out for yourself and if it doesn't work out for the fish, move on to another reasonable option.

After all, reefing is pretty much like anything else; live and learn.