color is definatly due to diet there are some firm white color meated trout that taste real good also the longer the fish are in the river or lake the better they seam to taste and the better they fight the best ones are the ones they stock as fry ive caught so rainbows in ark feeder streams that were as white as could be but had fantastic firm flesh and from what i gather from the dow they only stock the ark (atleast here between salid and canon city) with fingerlings due to the whirling desease. the dow says that the fingerlings are large enough that the desease doesnt bother them much but they still grow up "wild" and are more sporting to catch. and i might add much tastyer