The pink or red flesh color in salmon, trout, and char come from their diet. As noted earlier in the thread, the pigment is from carotenoids found in some fish diets. In high lakes the red flesh color typically either comes from zooplankton (red copepods, a tiny crustacean), or scuds (freshwater shrimp). Fish that target insects will have white flesh. Often you will find some fish with white and some with pink flesh from the same lake.

Given a diet free of carotenoids salmon will also have white flesh. They have to add carotenoids to the feed of farmed salmon to give them the pink color that consumers demand.

Fishnfella, brook trout definitely have white flesh unless they get the caratenoids in their diet. I've got a nice photo of two brookies side by side: one with white flesh, the other pink. They aren't able to utilize the copepods as readily as rainbow so in high lakes they will typically have white flesh while rainbow will, more frequently, have pink flesh because they can, with their more closely spaced gill rakers, more efficiently feed on zooplankton.

Brian