What is this glittery stuff?

[Stacey269]

My black mollies have recently gotten some weird thing on their heads. The top of their heads looks like there's some glitter-looing stuff. It's shiny and different colors. Has anyone ever encountered this before. I'm guessing someone out there has, or else it wouldn't have affected ALL of my black mollies. Is there something wrong, or is that just how they begin to look when they get old?

 

[ger87410]

Are you sure that it wasn't a trick of the light? My black sailfin molly has always been multicolored.