Fish are well known to see color. We learn this in elementary school science classes or when watching David Attenborough documentaries; yet, is that true? Yes! Fish do indeed see colors, which influences their response to lures.
Evolution has enabled fish eyes to adapt well to their environment, adapting visually depending on habitat and light levels. For instance, species living in shallow waters with reduced turbidity usually possess sharper all-round colour vision.
To fully grasp why, we must explore how light travels through water. When sunlight strikes its surface and falls onto water bodies, most is reflected back and absorbed into the subterranean environment; once there it is attenuated through scattering and absorption processes. Red wavelengths with lower photon energy penetrate less deeply than their blue and violet counterparts - hence why red fishing line often seems to disappear into murky depths instead of simply turning grey over time as it travels through its column of travel.
Fish have evolved specialized rod cells to detect colors in order to compensate for their limited vision, providing maximum sensitivity in minimal lighting from both natural and bioluminescent sources. Furthermore, those living at greater depths have shed cone cells for these rods so as to detect movement or contrast even in darkness.
