If they do well, they still are more likely to harrass any new fish added later. I've just heard of too many people trying to take all the rocks apart to catch damsels after they get more comfortable and mean. That clown/damsel could be a problem too, but it did sound like on the first day he asserted himself and proved his superiority, then on the second day all was well.
Try gobies, blennies, cardinals.
"Life may not be the party we hoped for but while we are here we might as well dance!"