I've always read that you shouldn't have more than two clowns in a tank unless it's a large tank. But there seem to be a few tank out there with multiple clowns with good results. Also I was just watching coral reef videos on uverse and there was a scene with a carpet anemone that looked to be 18-24" across with six or more percs living in it. And there was another with countless occys amongst some anemones all in very close proximity. So, how many clowns can you really keep together?