What size are the 3 percs? Are they all the same size?
Here is a quote from Wilkerson's Clownfishes:
"Because social surroundings determine gender, clownfishes from the Amphiprion genus can form a pair from any 2 juveniles. Two well-cared for small clowns can become a male/female pair, or one large clownfish (presumably already female) and a smaller one (adolescent or male) can also form a pair. Avoid pairing 2 large clownfish, because they will probably both female and ... may duel to the death."
"If you already have one clownfish and are introducing a potential mate, make arrangements for the newcomer's safety. Additional hiding spaces for the second fish allow it to find an unclaimed sanctuary. Better yet, add the two fish to a broodstcok tank at the same time so that neither one has a prior territorial claim."
She speaks about 2 fish, but you have 3. I hope this helps, at least somewhat.