It’s a question that has perplexed many thinkers of the world: If we don’t see air, do fish see water? We go about our daily lives surrounded by billions of air particles that we cannot see or touch. Like our habits, fish have a similar environment with the water that surrounds them. Is water to fish like air is to our eyes?

The simple answer is no, fish do not see the water that surrounds them. The brain works in a marvelous way to help filter out what we do not need to spend our time processing. The brain of a fish works in a very similar way when it comes to seeing their environment.

Why don’t fish see water?

The brain is constantly working to process incoming information in order to help us survive. If our brain thinks something should be filtered out to save vital processing power, then it will see it as an environmental noise.  

An environmental noise is any kind of “noise pollution” that you become accustomed to experiencing every day. Each species will have their very own set of environmental noises that their brain works to filter out. 

Take a look around, and think about the things that you are seeing in front of you. Now, without trying, did you see your nose protruding into your vision? No. Can you see the air particles that are constantly swirling around you? No. These things have been filtered out of your everyday vision, since they are not necessary to your daily survival. 

A fish’s brain works in a similar way to filter out the environmental noise that they experience. Because of this, they view water the same way as we view our air. Their brain simply filters out the sight of water to save room for other important processes. They view the water that they live in exactly how we view the air that surrounds us. 

Since we see water, can fish see air?

When we are swimming, it is very clear to us that we are surrounded by water, mostly because we can see and feel it around us. Since there has been debate about whether or not fish can see water, it opens the question as to if fish can see air?

The eyes of every creature on earth process colors and objects in their own individual way. Each object reflects the light in a different manner, resulting in how we see it. This is called refraction index. 

Air has an extremely low refraction index, making it impossible to see. Neither us nor fish can see the air in the environment.

Do fish see clearly underwater?

With all other questions aside, you may start to wonder about the general vision ability of the fish. When we are swimming in their territory, our vision underwater can be a bit blurry. Our ability to see through water is lacking compared to our vision when we are on land.

So what does the world in the eye of a fish look like? The structure of the eye in a fish is actually very similar to ours, with the differences being in how they refract light. The main difference in our eyes is the outward shape.

Our eyes, along with many other mammals, are generally flat. Fish have round eyes, giving them the “bug eyed” appearance. When we swim under water, we rely heavily on an underwater face mask that helps us to see. We need that extra layer of air in the goggles, since the density of air and water differ greatly when it comes to viewing the world around us. When the density of the environment in which we are trying to see through is heavier, the angle in which the light refracts is greater. The flat shape of our eyes are not ideal for this environment. 

The round shape of the fishes eye allows them to refract the light in a different way. A round lense is optimal for bending light. This means that in their underwater environment, their vision is quite impressive. A fish can see much better than the average diver in their underwater home.  

Which underwater creatures have the best vision?

When it comes to vision, some marine animals have better vision than others. Their vision abilities will differ depending on the environment in which they live, and how much light is available to them. The underwater creatures with the best vision include:

Octopus

The octopus has some of the most advanced eyes in the marine world. With more than double the amount of the nerve endings in the human eye, their vision is supreme in the underwater world. Scientists continue to study the eyesight of the Octopus, and are continuously intrigued.

Barrelyes

The Brownsnout spookfish (Barrelyes) live deep in the ocean, sometimes up to 2,000 meters below the surface. Because of this, they require some of the most advanced vision of all marine life.

Mantis Shrimp

Mantis Shrimp have such impressive eyesight due to their ability to move each eye separately. Their eyes also have twelve different color receptors, while the human eye only has three. 

Cuatro Ojos

The Cautro Ojos (Four- Eyed Fish) does not have four eyes, but instead has two eyes that are each split individually in half by a tissue membrane. They use two parts of the eye to see underwater, while using the other parts of the eye to see above water. They have an incredible sense of double vision.

Each of the species listed above have created their own set of individual requirements for the world around them. No matter the waters that they live in, their vision is their best tool.

Summary

Just like us, fish rely on their vision to maneuver throughout their daily lives. With each day that goes by, their eyesight develops in ways to better suit them to survive. While fish may not see water, they do have wildly impressive abilities to see the world around them!