I agree with Shawnie.
We had a 29g (It busted, but we still have the fish in a big bin with the filters and light running) with a full grown Angelfish, 4 Zebra danios, some Ghost Shrimp, 2 Dwarf Gouramis, and a RTBS. We didn't have any problems with the shark because we had a big rock formation that he called his own. They really are awesome fish to have. I would say it depends on the fish, the environment, the tank mates, and the size of the tank. I think you could house a happy one in your tank without any problems. That's assuming you have a portion of the tank he could claim.