Hmm, many things can cause the scales to look like that. Possible injury if he scraped up against something, poor water quality, or parasitic or bacterial infection can also be causes. Aquarium salt is very good for them (follow directions on box as to how much for your tank size) and if you think it's improved since you got him, it may continue to get better on it's own. I don't know enough yet to offer any other advice so I'll let other chime in on that. It does look like more of an injury to me as well rather than some sort of infection. Let us know if he keeps improving and so glad you "rescued" him. He's a cutie for sure!