Hard to tell what's going on from those pics.
The large dark spots could be the discolorations you see on fish when they scrape up against things.
IME the light coloration can be caused by lots of things. I see it in my foxface whenever it's slightly stressed. Could be another fish harassing it. Fish may also have light coloration when they are sick (like an infection) or have parasites (ich, velvet, etc.).
Also, I can see the ridge of the fish's spine. This tells me the fish is undernourished and doesn't have enough body weight.