And no it is not so beady eyed birds can catch a fish supper more easily...
Beautiful shiny scales with metallic sheen that fish possess have made for endless discussions over the years that can now finally be put to rest.
It is due to a sophisticated system of crystals that enhance light reflection and may help fish hide from predators in the wild, scientists in Israel are reporting.
In the new study, Lia Addadi and colleagues note that researchers have known for years that guanine crystals in the skin underneath the scales of fish reflect light to produce a mirror-like sheen.
This silvery reflectance acts as a form of camouflage that helps protect fish from predators as fish swim near the water's surface