Illumination of the aquatic environment to a large extent determines the motor and nutritional activity of fish, and color vision is used by them to recognize aquatic and plant organisms by their color. In some fish, color vision serves to reflexively change color for protective purposes.
Daily changes in the intensity of illumination are the cause of daily vertical migrations of fish. For each fish species, there is a certain limit to solar radiation, above which the conditions for them become unfavorable, and then they sink to a depth or take shelter in shaded places and stop eating. This is confirmed by the behavior of fish in cloudy weather – they remain active throughout the daylight hours. By the way, invertebrates, crustaceans, leading a bottom or bottom lifestyle, do not tolerate direct sunlight. Continue reading