not sure maybe he is just stressed out becasue of the new envoirnment you have put him in this should pass be sure that he doesnt get bullyd though i lost a very good looking orino that way. but imo i think it has to do with the diffrence of your and his old water parameters is all the diffrence might have stunned him he should get used to his new tank in a bit.
Yes. Dominance plays a role in coloration. The more dominant fish colors up more attracts the females appears healthier, etc. Natures way of ensuring the strongest specimens survive, and reproduce.
your monos threatened now that his not the dominant bass.. is it just the two in there.. dont be too surprised if you see them scrap a little now and then, its just them establishing whos gonna be the alpha.