Black on a foxface's . . . er, face?

[f14peter]

Just curious, but while perusing fish stores I've noticed that there's some variation in how black the black stripes on a foxface is. Does that make any sense or am I just re-enacting a scene from THIS IS SPINAL TAP?
Some seem very deep black, while others are lighter black, almost maybe a dark charcoal grey.
Any significance to that, maybe health or age?

 

[xdave]

Richness of color is often a sign of health as well as how comfortable a fish is with his surroundings. Foxfaces in particular may show varying degrees of night colors in the relatively bare tank of a lfs.