Nice scape bro!
Continue doing what you have been doing and keep a check on your water parameters k!
A tang is quite fierce on the system with their poos! :S
Anyway give you a good news, from my own experience, I think zoas which have suffered from zoapox can recover from the disease and continue to survive and propagate. It has happened to me before so I can vouched for this. However, one thing definite is that you must look into the root of the zoapox problem ie. lightings, addictives, water parameters etc and remove it. Otherwise, the problem will recirculate itself someday and you are still going to lose the zoa.
And zoapox is not really the end of the world, truly. Don't look it as something that bad, like I said before it's just a warning alarm from your zoas to you. Quoting from zoaid.com, the author believes that a good seawater dip/change can help to elevate the health of the zoa to fight off the disease which I believe till now works. So give it a try someday k! (:
Above is just my 2 cents ah. Hope it works for you k! Happy Chinese New Year!
HUAT HUAT Reefing,
Marc J.