emerald crabs, porecelain, pom pom crabs(my fav) would all be great. stay away from arrows, i kept on myself and i believe he killed my pistol shrimp tho im not sure. 2 clowns and the firefish would work with adequate rock and water changes, I have two clowns and a YW goby in my system and its running great(14 biocube as well) make sure to add things slowly though