What are the advantages of the dark-dorsal and light-ventral colorations of the perch?

Answer 1

It is a camoflauge technique to hide from either predator or prey - from above, the dark dorsal makes it harder to see against the background of the dark depths; from below, the light ventral makes it harder to see against the lighter back ground of sunlit waters. For obvious reasons, this skin coloration is only seen on organisms living in the euphotic zone.

Answer 2

The dark-dorsal and light-ventral coloration of a perch helps it blend into its environment as a form of camouflage. The dark color on top makes it less visible from above, while the light color on the belly helps it blend in when viewed from below. This coloration also helps confuse predators or prey about the true size or shape of the perch.