Orange Mollies With Grey Stomach?

[TanksRUs]

I was doing my fish feeding today, and when I was finished making sure everything gets their food, I left. I came back in about 10 minutes and realized all my orange mollies have a grey stomach.
Is this normal? It might have something to do with the food, as I gave them brine shrimp.

 

[OldMan47]

It is not unusual to be able to see the color of fish food reflected in the fish's abdomen color. You will also notice that the fish's waste reflects the color of what it is fed.