How fish see color

Most fish see colors. As with people, the retina of a fish’s eye contains two types of cells: cones and rods. Cones are used for day vision and are the cells that discern color. Rods are used for night vision and cannot distinguish colors, although they can discern light intensity. In most freshwater fish, the eyes possess both rods and cones, although night feeders like walleye or fish that live at greater depths have more rods.

Research suggests day feeders like bass, trout and salmon are more sensitive to color than night feeders like walleye. Studies have shown that rainbow trout and Pacific salmon have color vision similar to that of humans. They can distinguish complementary colors and up to 24 spectral hues. Other studies have shown that brown trout are capable of sharply focusing on near and far objects at the same time and can clearly see different colors at different distances.