I have had a tomoni for about a year and half and since day one he would show similar white spots randomly. They would come and go and he always seemed healthy. Never scratched, or anything. I always thought it was just scratches from diving into the rockwork so dang fast and scratching himself. When I added a cleaner shrimp, he was the first to get his cleaning, and was the shrimps best customer. However, up until recently I was forced to pull all of my fish and qt them. All of my tangs underwent a freshwater/methylene blue dip for 5 minutes prior to qt to check for flukes. It did look like some dropped off. So between the activity with the cleaner, and the what looked like flukes from fw dipping, I would have to think flukes as well. And also, since he has been in qt, about 5 days so far with copper, he has never looked better! I would listen to humblefish and treat for flukes, then go back to qt. observe for any secondary infections or parasites and keep a close eye on him for a while.