Blue fish are exceedingly rare in the ocean, because they would be highly visible until they reached the lightless waters of the bathypelagic. Meanwhile, red fish are fairly common because red is the best camouflage in deep water. A fish like a red snapper looks red at the surface, but as it descends, the redness appears to fade away until, at around a hundred feet, it becomes virtually invisible to its prey and predators. This is why snapper spend almost all their time at between fifty and two hundred feet.
