I've seen these on bass myself. I think they are akin to birth marks or could be scar tissue but I have nothing to back this up. I see this on wild bass but don't see it on my feed trained domesticated bass at all.

Regardless I don't believe it's anything to worry about. As far as pale or fish color in general that depends on your water color and turbidity.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.