Is My Crayfish Sick?

I noticed today that the tail area of my crayfish is turning red. I don't know exactly what type of crayfish I have, and I was wondering if this is a sickness or if this is supposed to happen. It's already molted about four times so I would think that this would've happened already if it was natural, but I'm not sure.

 

Coloring up is usually a sign of healthy aging. Foods can also contribute to color.