Do they do well in groups/. I'm getting a corner tank, somewhere between 40 and 60g (undecided as of yet) and I was really interested in getting a Long spined sea urchin with some banggai cardinalfish. So I think I could have about 8-10 cardinalfish, would they be alright in groups like that? Also, if I get a tank closer to 60g, I'll probably get a pair of clownfish and a goby of some kind. Just wondering, would that be okay?