If your doing a clown harem tank you need to add all of them at once or they will fight. Their is a couple of exceptions, if they are consistently about an inch to inch and a half. You can leave one female in the tank and add super small males/ non-sex clowns. If you add them all randomly you could have some major problems. I have a Circus or Harem and mine is awesome! Love the little guys to and gal to death. If you want any advice feel free to PM me. Just trying to save you some head ache 🙂