Aquarium rocks changing colors of oscars

Is it true that depending on the color of the rocks on the bottom of your tank, it affects the color of the fish? Example; I have black rocks on the bottom and a black oscar, do the rocks make him darker? If the rocks on the bottom were white would he be...

lighter and would his orange stand out more? Because when I first got the black oscar he was so bright and orange and now hes pretty much all black with hardly any color.

maybe the rocks reflect on his scales...