Water being a transparent liquid, we cannot see it. It is the same for fish. To see a transparent medium, it is necessary to see it from the outside, and, more precisely, we will see the separation surface of two media (assuming their different optical index of refraction).
Fish see the currents close to them with the movements of the particles, but they do not see the water itself. Moreover, if they saw the water, and if we saw the air, we would see nothing.
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Can fish see the water they are in?
Fish see water as we see air, over long distances with the decrease in visibility behind the molecules that with distance, accumulates in our visual line of sight.
How do fish see?
The view of fish. It is said that fish are completely “blind”. But what is it exactly? Do fish really see nothing at all or can they perceive certain things? After all, they do have eyes…
Do fish have good vision?
With eyes placed laterally without any eyelids, we don’t see them blink or flutter… So, do fish see? According to scientists, they would have a bad vision at a distance, therefore rather myopic. But they see.
A fixed gaze indicates that their pupil does not contract, but this famous immobility of the gaze offers them a wider field of vision. So, the little fish in the water can’t see very well, but it sees more widely than we do.
What are the differences between fish?
In the sea, in lakes, as on land, in the great animal kingdom there is an unstoppable rule: predators and prey are opposed and, therefore, have different physical characteristics depending on their situation.
The same is true for fish, especially with regard to their important sense of sight. Thus, while predatory fish will have eyes placed forward, in order to spot their possible prey, prey fish, on the contrary, will have lateral eyes in order to better distinguish if predators are chasing them!
The 3D vision is then wider in predatory fish than in prey fish. As for the latter, they have a less precise vision area, but which is quite convenient for them to watch the surroundings…
The vision of fish
Fish see in colors depending on the species (if they live in deep or shallow water). They are able to distinguish red (the first color absorbed by water), yellow, orange and violet.
They also have a retina capable of absorbing a very large quantity of light, which allows them to have a good night vision, much better than that of the cat which is however famous.
Their binocular vision allows them to see far away and in relief.
How do fish see day and night?
Diurnal species living in shallow and clear water seem to have a good vision of colors, and conversely those with nocturnal, crepuscular habits, living in turbid waters seem to be more sensitive to luminosity than to colors, i.e. they distinguish subtle shades of gray and brightness, even in low light.
Among our carnivores, it is safe to say that pike, perch, black bass and trout have good color vision, unlike catfish, eel and eel. However, we are not sure that all shades of the solar spectrum are well perceived, and in particular, it seems that some species lack blue-sensitive receptors, such as perch and zander.
