If there the ones i had come on a frag, they are very tough. I have read that copperbands eat them. I had to basically throw away my frag, saved six of 30+ polyps. FW dips, Coral Rx dips did nothing.
Worms are your friends, usually... If they're irratating your zoas, just attack the particular offender. Usually they are either buried in the sand, or hiding in a rock. If the bad seed is in the sand, just dig it up and relocate. If it's in the rock, give him an epoxy tomb.