Its looks like it might be dyed. Dyeing fish is barbaric and cruel and usually results in shorter lives for the fish

If i was you i would return the fish and would tell the shop i will not shop there unless they agree to stop selling fish like this. Also tell them that you will tell your friends not to shop there too. While this sort of thing is legal the best way to stop these sort of fish being sold is to make stores realise that it is not going to be profitable to sell them, so dont shop in shops that sell dyed or tattooed fish

No, in Michigan. But I wouldn't have bought him if I'd known he had been dyed. It's too cruel. Is it possible to speed the process of regaining his natural color?

As far as i know there is nothing you can do but wait

I will say again that if you dont like this practice then
tell the shops that sell these fish that you will not spend
a penny or a dime in their shop if they continue to stock
these fish