what is the lighting on it? that is what will decide what kind of corals you can have. but for that sized tank i would suggest some brightly colored zoas, and ricordias. something that will stand out nicely and wont grow so much that it will be to much for the little room it has.
It is possible that you can feed enough to keep Zoanthids alive. But then you will have brown Zoanthids and nutrient problems in the tank. I recommend against this but it is possible.