are they any bumps on the body of the zoas...? not the face, but on the sides..? my friend is suffering with zoapox right now... or is there any fuzzy stuff around them too...? like on the base...? it could also be dirty razor blades, or infections... maybe your rack or wherever you have the mother colonies has a colony of bacteria... move them to the sand or some new spot after you frag so they can heal...
post some pics...