Most fish can see in color. As in people, the retina of a fish's eye contains two types of cells, rods and cones. Cones are used for day vision and are the cells used to see colors. Rods are used for night vision and cannot distinguish colors, although they can judge light intensity. The eyes of most freshwater fish contain both rods and cones, though day feeders tend to have more cones, and night feeders more rods.
In theory, then, day feeders like bass, trout, and salmon are more sensitive to color than night feeders like walleyes. 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 that they can clearly see different colors at different distances.
But light behaves differently in water than it does in air. The various colors of light travel at different wavelengths. The longest wavelengths are the reds, followed by oranges, yellows, greens, blues, and violets. When light travels through water, some of its energy is absorbed, and the longest wavelengths are the ones absorbed first. Thus, the warmer colors fade out and gradually appear black as light penetrates the water column. Red light is almost completely absorbed within the first 15-20 feet. Orange penetrates to 30-40 feet, and yellow to 60-70 feet, while green and blue remain visible for as deep as the light penetrates.