It is actually a myth that bass are colorblind. Fish, including the bass see through their eyes and are also able to detect color. The eyes of fish are also usually rounder than most mammals due to the refractive index of the water; focus is achieved by moving the lens in and out so as not to distort things. The bass fish’s eyesight is one of its most important senses as it helps them locate food. They are considered “sight feeders” and use their other senses as well as support for their sense of sight.
Fish eyes are designed with a cornea, an iris, pupil, lens and a retina. The process of actually turning light into images all begins at the retina. This parabolic shaped surface located at the back of the eye is where photons of light are received and then transformed into electrical impulses for interpretation by the brain. The retina contains rods and cones (the photosensitive receptors that accomplish the task of receiving light and transforming it into impulses to direct it through nerve fibers leading to the brain).
One prominent characteristic of the fish eye from the outside is its bulbous nature. The outer layer of the eye known as the cornea is a dome shaped transparent layer that is the first to receive light. With the terrestrial vertebrate eye, light travels through the air and hits the cornea. Because the air and cornea differ in density however, the light is then refracted meaning it is bent and directed into the opening known as the pupil. Water and cornea are of about equal densities, so there is often little refraction with the cornea of a fish eye.
Because these creatures inhabit the water, that absorbs, scatters and bends light to a degree that makes seeing under water difficult and also different than seeing in air, fish have evolved out of necessity and are designed with specific anatomical characteristics in the eye that help them see underwater. In water colors behave differently and are not easily differentiated as they are when seen in the air. Therefore, fish eyes to varying degrees are equipped with retinal cones that can detect different ranges of color.
It should be noted that there are two types of photo receptors on the retina of the eye. The first are rods which are sensitive to light in general, and the second are cones which are sensitive to colored light. The ratio of rods and cones varies according to a fish’s habitat. There are also different types of cones located within a fish retina and each is sensitive to a different range of color. Most fish, similar to humans have red, green and blue sensing cones however the range of each color sensed can vary. Additionally some species of fish have been found to perceive ultraviolet light and also have patterns on their bodies that can only be seen under UV light. It is presumed that this is for attracting the attention of conspecifics.