Another thing has to be said about the age and maturity of the tank. In my earliest years with my tank, hippo tangs were impossible to keep. they got ich almost immediately, and never made it for more than a few weeks at the most. Now (after 11 years maturity) I never get ich, and hippo tangs are very easy to keep. That said, my personal rule of fish keeping always was "hardiness is inversely proportional to price"...in other words, the more you pay, the more likely to die. Unfortunately true much of the time. I'd suggest blue damsels, maroon clown, maybe the extravagance of a yellow tang. Keep it at that while your tank matures over the years.