big white spot

[ganowicki]

I have a small Naso Tang and it seems to be doing well. It eats like a pig and is full of energy, however it has a large cotton looking spot on it's dorsal fin. so what is the best way to get rid of this spot?

I have heard several things, like garlic extract, malachite and RxP help get rid of this, but I would love to hear other people's experiences

PS I do not have a quarantine tank