The other thing with schooling fish in our small tanks, is that they can outcast the least dominant fish, and they will die. In a lot of cases all the way until 1 is left.
I've seen this in anthias and chromis. Although in my 180 with the chromis the numbers have dwindled to 4 (from 10) and the outcast fish lives in the corner of the tank. He looks like a starving runt, but he comes out to eat, and nobody really picks on him. The other 3 are now twice his size and fat and happy.