WHAT AND HOW DO FISH SEE?
The structure and capabilities of a fish eye show clear adaptations to its visual environment.
Like in most vertebrates, a fish eye contains light-sensitive visual pigments. Each pigment absorbs a different wavelength from the spectrum, allowing the beholder to perceive different colours. The perception of colour also depends on the viewing distance, depth and the background of the object in focus.
Depending on which wavelengths of light are able to penetrate through the water, light determines to a significant degree what colours fish can see and how their own colours look to the eyes of their neighbours. For example,