no they dont molt the old colorings and become a new coloration... its more like if you have a photograph, and you put a cookie cutter on that photograph, so you can see somebodys face inside the cookie cutter. well lets say that cookie cutter starts growing.. and soon you can see a couple faces in the cookie cutter, and then some background.. and so on.
well.. imagine the cookie cutter is the fish, and when the fish is a fry, you can see one or two dots on its body.. well as the fish grows, the dots appear more frequently.. until you end up with my lovely Leopold. a white platy with peach fins with peppered purpley red dots all over his back