From zoos-dieI always do a fresh water dip on a new zoa colony before it is added to my tank which will kill any nudibranch ( if not the eggs). BTW zoa munching nudibranches will become the color of the zoas they are eating so they can be hard to see..
IN Feb. of 2007 I added a new colony on zoas. All was fine for 2 weeks then I notice the new colony was not opening and polyps were disapearing. I mean they were just wasting away. It rapidly spread to the my other zoas.
I did a lot of research - read the threads that Techno-Vicki just posted a link to above. Long story made short. I lost the new colony, all of the orange colony and all of the teal ones too. I probably lost about half of the polyps of the other 3 colonies but I was able to save them. and they are doing much better and slowly growing again. They still do not look as good as they do in that pic above tho. It was really heartbreaking.
The teal colony started as an original HH on my LR when it was first added to the tank. About two months of the LR being in the tank One little teal polyp suddenly showed up. A few months later there were 5 polyps and a few months later they really started to grow. There were over 125 polyps in that colony when they caught the wasting disease. I could not pull that rock out of the tank to do a FW dip as it was the main stuctural piece of LR in the tank. It was very painfull (still is) I have not talked about this wasting disease very much but this seemed to be the place to do it to possibly help other zoa keepers.
I am going through a similar problem with my zoanthids. I have lost 2 colonies and 2 other colonies have been affected but I am hoping they may survive. I found some great information on unexplained zoanthid wasting disease on RC's Zoanthid forum. It started with a new colony that I had added about two weeks before. (I always give new Zoas a fresh water dip). I threw that rock out right away but then a colony on my base rock started deteriorating There was nothing I could do but watch. A week later the colony of well over 100 polyps was completly gone. My other colonies did not show any signs of it until the 2nd colony was nearly all gone.
Fresh water dips seem to have slowed the progression of this wasting disease on a couple of my colonies along with small water changes every day.
I think I have saved these but have probably lost about 2/3 of those colonies. I have another colony that is clearly a different species and they have been unaffected.