I'm gonna have to be the one member to disagree w/ the substrate view on coloration. My reason is due to my MM's. They have been in bare bottom tanks since they were pups and the bottom of the tanks have all been painted black. In my experience they coloration is due to the individual ray because the coloration on my male is much darker and they have been together the whole time eating the same food and they came from the same batch.......
I'll post pics of the male when I take em. Also, the parents coloration were nothing like this.


I'll post pics of the male when I take em. Also, the parents coloration were nothing like this.