Labored breathing and fast demise fits a few diseases and parasites. The most notable is Marine Velvet. Sometimes the disease strikes so quickly that the aquarist just finds dead fish and doesn't see that the fish was stressed or having respiratory problems. A copper treatment would cure fish of that parasite.
It may be a couple of more or less minor things piling up to create a significant stress in the fish.
A friend of mine tried an experiment last year. He got his 180 gallon tank ready with LR, snails and shrimp and let the tank age for 6 months. So far so good. He added ammonia water to boost the quantity of bacteria to handle the bio load and then put in many fish at one time. Most the fish died in 10 days. I think the system, though the nitrogen 'handling' bacteria were numerous, couldn't handle the general organics introduced so quickly. There are many things on the microbe level going on in a young aquarium and these all change again when fish and foods are introduced.
Back to the anemonefish. . .This fish is an omnivore and needs at least 30% vegetable matter in its diet. If and when it does begin eating, have foods, vitamins, fat supplements and beta glucan ready that match the omnivore suggestions in this reference:
http://archive.reefcentral.com/forum...hreadid=785228
The cotton like patches. We need to be careful about trying to figure out what they are. Do you know Lymphocystis when you see it? If not check this reference out. It has a photo in it:
http://www.wetwebmedia.com/viraldislymph.htm
Do the cottony things look anything like that?
The pale patches you mention make me consider tuberculosis. Not common. But if the patches have fibers in them, like cotton as you called it and it doesn't definitely look like Lymph, then I'd suspect an external fungus.
Very rare but fungus can occur. Usually it is secondary to a serious injury or severe stress or another disease/condition. It is very difficult to cure, but not impossible.
You have to make the diagnosis since I have no photo to go by.
If you're convinced it is fungus, then I would treat it like it was
Saprolegnia. I'm only familiar with the 'old medications' for a fungal infection, which I don't think you'll have access to. Because fungal infections spreads quickly and usual fatal, I just put my fish down.
However, if it is fungal, you may try Nifurpirinol (which can be combined with Neomycin (a gram negative antibiotic)). This combo has met with some success to the best of my knowledge.
If you diagnose fungus, stop the copper treatment as soon as you have the above medications and then begin treating the fish that way.
Watch water quality including pH, ammonia, and nitrites closely. Your goal is make ammonia zero and nitrites less than 0.5ppm for this fish.
I'm sorry I can't be of more help. If you have more information or additional photos, I'll try again. Good luck!
