Can fish see water? a complete Care guide

Can Fish See Water? 15 Things You Need to Know

There was once frequently asked that can fishes see water or anything? Well, whenever your fish follows your hand or move quickly to the top at the feeding time, shows that fish can see. Today we are here with an interesting question can a fish see water?

No, fish can’t see the water around them, just like us as we can’t see the air around us. This raises several questions in turn Like why they can’t see water when they can see everything else clearly.

The basic mechanism behind this behavior is our brain is trained in this way to avoid any unnecessary detail. To us, the air is not significant to be remembered same is the case with fish as well.

Now let’s take a look at how fish see everything around them.

Why Fishes Can’t See Water Around Them?

The answer lies in the intrinsic working of the brain. The brain of all the fishes, amphibians, reptiles, birds, and mammals is adapted to intentionally ignore insignificant environmental stimuli.

Water is present in abundance around the fish if their brain is focused on all the components of water their brain will soon run out of its processing capacity. For the brain to function efficiently it is crucial to only direct it toward the vital stimuli.

For example, if we focus on all the noises or smells around us it will be very hard for us to process this abundant information. So, without knowing we have stopped processing our own body odor.

Similarly, a fish’s brain works on the same principle to filter out background stimuli to improve its functioning. This helps in improving the memory and ability to perceive critical stimuli.  

Do Fish see water or have Sense of Vision?

Not just vision fishes are equipped with all the basic senses such as taste, smell, touch, and hearing. A fish’s eye is quite the same as ours in anatomy and working as well.

Components of Fish’s Eye:

A fish’s eye is composed of more or less the same components as that of a human eye. They have a similar cornea, lens, iris, pupil, retina, and all the photoreceptors. The nerve supply is the same as that of is the optic nerve.

These components are arranged similarly to the human eye. Fish do not have eyelids for protection.

anatomy of Fish Eye
Source: Wikipedia

How Fish’s Eye Is Protected Without Eyelids?

Some other queries we frequently get are, do fish have eyelids? No, they don’t have eyelids and that brings us to the next query that if fish do not have eyelids what protects their eyes?

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Well, humans have eyelids to clear the dust particles and prevent them from entering the eye. Being underwater creatures, fishes do not have this problem, their eyes are constantly getting washed away by water.

Thus, fish do not need protection at all for their eyes.

How Do Fish See or Process Image?

The processing of images in fish is similar as well. The light from outside first enters the eye through the cornea and from there it passes through the pupil and lens. As the lens focuses the image on the retina, it is perceived by photoreceptors such as rods and cones.

Photoreceptors efficiently convert these stimuli into electric signals. These signals are conveyed to the brain through the optic nerve. This way an image is made on the back of the mind. It takes milliseconds for a fish to focus, form and process this image.

Why Do Fish Have a Greater Range of Vision?

Fishes are gifted by nature in terms of the greater field of vision and wider view. Their eyes can capture a wider field in a single glance.

This property is due to an exceptionally spherical lens. This lens has a panoramic view helping the fish to stay aware of their environment.

There is a downside to these wide-vision lenses, they come at the cost of focused vision. Fishes can not focus on distant objects; thus, they appear blurred to them.

Are Fish-Eye Lenses Actually Named After Fish’s Eye?

Yes, that’s interesting and true, fish-eye lenses that are famous for their panoramic view, are named and developed after fish’s lens. So, these lenses are paired with focusing techniques to have wide-angled focused images in cameras.

What Colors a Fish Can See?

Fishes are capable of perceiving more colors as compared to a normal human eye. There are only three primary colors (red, green, and blue) that are perceived by humans.

In contrast, fishes can see more than these primary colors and can differentiate between various shades of colors.

Moreover, fishes can not only see visible light but also, can perceive ultraviolet light. This ultraviolet light is beneficial in some species while looking for food.

Thus, it is safe to say that the fish world is much more colorful than ours.

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Is It True That Fishes Are Short-Sighted?

As it is said earlier fishes do have a wider vision, but they are also unable to see distant objects. The objects at a distance of 100-150 feet are visible to fish but a blurred image is created at the back of their head.

Thus, it is usually said that fishes are short-sighted or near-sighted as they can perceive near objects with far greater clarity.

How Do Fish See World Underwater?

A fish’s vision underwater is quite different from ours. They have a panoramic wide-angle view, but they are unable to focus on objects far from them. Moreover, they can see a world of colors due to their ability to perceive colors other than primary colors.

Due to their ability to detect ultraviolet light, they can see colorful objects and prey even in the darkest parts of the ocean.

A fish’s view underwater is affected by many factors such as quality of water, the flow of water, algal growth, sunlight reflection, availability of light, and much more. Thus, their vision is not always the same.

How Can Fish See in Murky Water?

Fishes have adapted themselves according to their environment in every aspect. Similarly, when it comes to vision it also depends on their habitat.

Fishes inhabiting murky water or areas with low light have adapted themselves to see any obstruction on their path. Although vision is not clear, they can swim and see any prey or predator easily.

Can Fish See Air?

While answering the question that can fish see water opens up another debate that can fish see air?

The answer is simple, no, fish can’t see air. The reason behind it is that to see an object in the different mediums the refractive index of the two mediums should be different. The refractive index of air is very small that is 1, it is impossible to see air.

Thus, neither we nor any fish can see the air around us.

Is There a Fish Without Eyes?

Mexican cavefish are practically blind as their eyes are atrophied due to disuse. Mexican cavefish inhabits darker areas of the sea such as caves where there is no trace of light.

Thus, their eyes are no longer functional. So, they are now called Mexican blind cavefish.

This discovery also proves that fishes living in a darker environment will sooner or later lose their eyes permanently.

Can Fish Live Without Eyes?

Fish can survive an organ loss such as losing their eyes only if kept in isolation. In the wild, blind fish can never survive because they can’t find food.

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Moreover, constant predator attack also makes it difficult for them to survive without eyes. A blind fish can only survive in two conditions, first complete isolation, secondly if it inhabits extremely dark areas of water.

Fish Disease Affecting Eyes:

Most frequently aquarium kept fishes suffer from Popeye disease, in which their eye is lost after infection or injury.

Popeye Disease in Fish:

Medically, it is also known as exophthalmos. If the infection is the reason behind the disease, it is contagious, and you should first isolate your fish to protect other fishes.


Excessive swelling of eyes leading to their protrusion out of their socket. Lethargy, loss of appetite, and susceptibility to various infections are commonly seen.

It eventually results in the loss of one or both eyes in fish thus known as popeye disease.


There are two major causes behind popeye.

  1. Infection due to unhealthy water.
  2. Injury or trauma from aquarium decorations.

How to Treat Popeye in Fish?

  1. Firstly, isolate that fish in a separate hospital tank.

  2. The first line of treatment is to improve the water quality.

  3. Check all the water parameters and do a thorough cleaning.

  4. Maintain all the water parameters in the appropriate range, especially pH, temperature, and levels of nitrate.

  5. Look for symptoms and if loss of appetite is seen go for antibiotic therapy. Any broad-spectrum antibiotic will be effective.

  6. If the condition of the fish doesn’t improve in 24 hours or if worsen look for a fish expert and seek immediate treatment for your fish.


Thus, it is clear from our above discussion that fishes do see and see quite a lot but fish can’t see water around them. Just as we can’t see the air around us, it is a highly developed function of the brain to omit any unnecessary stimulus from perception. This technique improves the brain’s capacity for perception and processing.

Fish can’t see air as well due to too little refractive index of air. Certain fishes are practically blind due to their habitat. Fish can also lose vision due to certain conditions such as popeye or injury.

I hope this article proved beneficial for you and answered some interesting queries.

Best of luck with your fish!!!

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