If the fish looks like they're "shedding" then there must be something causing irritation. Anything from ammonia, nitrates, current or an unknown substance.
A little more info will help narrow down the issue.
Are the fish at the surface gasping?
Are they laying near the bottom nearly motionless?
Have you tested your water? If yes, what were the results?
Have you added anything new to the system? Gfo, carbon, new equipment, new additives? Anything new at all?
Is this in your reef or fowlr?
More info will help.
Also if we can't narrow it down. Your best course of action is a large water change. I'd say a good 25% will help.
Like I said if the fish look like they're peeling or shedding. Then there is definitely something in the water causing irritation. A 25% wc will help reduce whatever is causing the issue.
Sony Xperia Z3