That link that BJ gave always shows up when somebody has receding zoas with spots on the polyps. I've seen that article about 20 times in my short 2yrs in this hobby. I thought I had zoa pox once, but it turned out to just be specs of sand. I have spent a LOT of time reading about zoa pox and treatment of zoa pox. That article seams to be THE CURE for zoa pox.
I'd do it. I'd do it NOW.
Fragging them doesn't do any good. The frags will develop zoa pox too. Buy some of that anti-fungal stuff and get after it man!! Don't wait any longer. Dip 'em! Dip 'em! Dip 'em!
Good luck.