Yea mine is eating 1'' to 1.5'' fathead minnows and I dont really see any oppritunity for bright coloring in that diet however while doing alot of research on LMB it has been sugested that adult LMBs may also munch on aquatic plants in addition to their normal intake of fish, frogs, crayfish ect.
The reason I ask about coloring is because I know that the foods many fish eat (such as oscars) will give them more vibrant colors and being in a tank gives us as keepers the great opritunity to give them the foods that make them much more beautiful than their wild counterparts who are limited in the foods they can eat.