again you are going to be limited to small fish that dont swim around a lot.
clowns some gobies things such as those. tang,angles, lions,puffers,triggers,butterflies, groupers, and alot of wrasses will not live long in a tank that wilnot allow them some swimming room. you have to look at the size of your tank lenght wise and then look at the adult size of the fish. if they dont have around 2x there lenght to turn around the arent a good choice for your size tank.
Mike