Cloudy Eye Fish Disease: The Signs, Causes, and Treatment




Cloudy Eye Fish

Sharing is caring!

If you’re reading this article, it’s likely because you’ve noticed something different about your beloved pet fish.

Maybe his eyes aren’t as vibrant as they used to be, perhaps they have a milky white tint, and you’re panicking wondering what it could be, or perhaps even thinking what I did when I first came across this – That your fish may be dying!

Well, worry no more. In this article, we’ll discuss the causes of cloudy eye fish disease, if it can go away or be treated, and how severe this issue may be if it persists.

What Is Cloudy eye?

The eyes of fish are similar in structure to a human’s. The outer layer, also known as the cornea, protects the inner eye structure from becoming damaged.

Just below this is the iris, which adjusts to allow more or less light into the eye. Behind this is the retina, where light is processed, then the optic nerve sends the processed information to the brain.

One difference between the eye of a fish and a human, however, is that the lenses in a fish’s eye are spherical. This is why you may have seen a ‘fisheye’ filter on photo editing apps.

If you’re familiar with how this looks, you’ll be able to clearly understand that a fish’s vision is clearer in the center and fuzzy towards the edges.

A cloudy eye is something that can occur in a fish, usually due to damage to the eye (since fish typically do not have eyelids to protect their eyes from damage). Still, it can also result from a fish’s immune system being low.

This typically looks like a cloudy layer, sometimes making the eye appear white or grey in color.

When a fish’s eye is damaged, this cloudiness may be present on the outer eye (on the cornea) or the inner eye (the rest of the eye structure)

You must note that outer eye damage is usually less serious than damage on the inner part of the eye, making it easier to treat and cure the cloudiness.

What Causes Cloudy Eyes in Fish?

Determining the cause of cloudy eyes in your fish can help you learn the next steps needed to treat or cure it.

Be sure to use this article as a general guide, though, and if you believe your fish may be sick for one or more of these reasons, be sure to consult an aquatic veterinarian. 


Your fish’s eyes may be a little cloudy or pale because this is just how they were born.

To be sure of this, you’ll need to be certain that your fish’s eyes have always looked like this since he hatched and that this cloudiness is present in both eyes to the same extent.

Some species, such as pufferfish and rabbitfish, have a naturally white sheen on their eyes, which can easily be mistaken for cloudy eyes.

If your fish develops cloudy eyes, you’ll want to first research your fish’s species, as it may be the case that cloudy eyes are common in your pet’s gene pool.

Ammonia Levels

When it comes to your tank parameters, you’ll want to keep the levels of ammonia low.

You can ensure this by using a filter, regularly changing the water, and removing any waste build-up, such as poop or uneaten food, that may settle on the bottom of the tank.

Ensuring that the ammonia and nitrate levels in your tank are both appropriate for your species and well maintained, will aid in preventing a build-up of waste. It’s recommended to ensure that nitrate levels are kept below 20ppm

This is commonly overlooked in new tanks, as many people often forget to monitor the nitrogen cycle in their new aquarium.

In short, if you regularly maintain and check the nitrate and ammonia levels in the tank are suitable for your species, then your fish should not acquire illnesses related to these levels or develop cloudy eyes as a response.

Chlorine & Chloramine

If you are using tap water to fill your tank, ensure that chlorine and chloramine have been removed.

You can remove chlorine by pumping air through the water to make it dissipate faster or letting the water sit for approximately 24 hours.

Chloramine can only be removed via water conditioning or heavy carbon filtering, which can be purchased at your local pet shop.

If the water is left untreated, these could irritate your fish’s eyes and cause them to become cloudy, as well as make your fish sick.


You should be certain to add any medication to your tank in the amount at which it was prescribed.

If you add too much medication, this can cause eye problems for your fish, such as cloudiness, due to either an adverse reaction to the medication or due to the effect of the medication on the conditions of the water.

Poor Water Quality

Another potential cause of cloudy eyes in fish is if there are poor water conditions in your tank. This can be caused either directly or indirectly, usually due to a weakened immune system.

This is common in new tanks, as fish adjust to new waters, and because several different things can cause poor water quality, there are a few steps you would need to take to reduce the symptoms of cloudy eye.

Suppose your fish are experiencing any other symptoms alongside their cloudy eyes. In that case, this could indicate a more severe illness, potentially caused by poor water quality, so get your fish seen by an aquatic vet as soon as possible, as they may require medication.

Poor Diet

A deficiency in vitamin A, which is crucial for healthy eyes, can also cause cloudy eyes.

If you believe this could be the case, making adjustments to their diet could be beneficial. Ensure they have the perfect balance of vitamins and minerals to stay healthy and happy.

If they’re deficient in other vitamins, this will lower their immune system, making them more susceptible to illnesses and infections, so be sure to give them a well-balanced diet so they can remain in good health.

Physical Injury

When determining what may be causing your fish’s cloudy eyes, it’s important to note both. If both eyes are cloudy, then it’s likely a serious issue caused by illness or infection.

However, if just one eye is affected, then it’s likely to be a physical injury or trauma to the eye. Sometimes it’s caused by fights between fish and it can result in discomfort. 

If you determine the cloudiness has been caused by physical injury, try to figure out what and when this could have been.

Possibly a sharp angle or point on some of your aquarium’s decor?

If not an object, it could have been caused by a fight with a tank mate. If housed with any aggressive species that may have done this to your fish, you may want to consider moving them to a different tank to prevent any future damage to either fish or even death.

This type of injury will usually go away by itself, but keep a close “eye” on it. If your fish contracts a bacterial eye infection, this could cause the cloudiness/milkiness to worsen, so if this occurs, be sure to see a vet.


Cataracts can also be caused by a parasitic infection, such as flukes. If this occurs, sadly, there is no known cure, as once the infection has set in, nothing can be done.

An infection of eye flukes usually results in blindness and is far more common in the wild than in captivity – but it is still something you should be aware of.

You should be able to distinguish if your fish is infected with eye flukes, as there will be other eye-related symptoms.

The fish will likely have an enlarged eye (known as popeye disease) with milky-colored spots on the iris.

In humans with cataracts, surgery can be performed to correct this. However, in fish, there are very few treatments available, and sadly, there isn’t much that can be done to remove the damage caused to your fish’s eyes.

Cataracts can also be caused by poor nutrition or genetic factors but can also be a symptom of old age. It refers to damage to the lens of the eye, which causes it to become opaque.

Cataracts can cause difficulty for your poor fish when it comes to navigating around and finding food. This is particularly difficult if they face competing for food at mealtimes with their tank mates.

Sadly, due to its many causes, it’s one of the most common eye problems in fish eyes and isn’t something that can easily be avoided.

The best way to prevent it is to ensure your water is always of the highest quality and prevent contaminations or outbreaks within your tank.


Parasites, such as flukes, can sometimes live in your tank due to poor water conditions, making cleaning much more difficult than just dealing with a build-up of algae and grime. They cause common diseases in fish too.

There will always be a small presence of parasites, which is harmless, but in the right water conditions, they’re unlikely to live very well and will not be a detrimental threat to your fish’s health.

An outbreak, however, can lead to deformities and death and be deadly to all species living within your tank. Similarly to bacteria, removing every trace of them is very difficult.

If you encounter an outbreak, and you’re certain that’s what it is, firstly, medicate your tank with appropriate medication.

Parasites can cause damage to your fish’s body, causing tears in fins, lesions, and other ailments, but the most common symptom is cloudy eyes.


To follow on from the parasitic infections, let’s look at infections more broadly. Whilst some can be caused by parasites, bacterial or viral infections can cause others. This affects the fish immunity by exposing it to diseases like fish TB. 

Both can be prevented with a regular cleaning routine and upkeep in the hygiene of the tank. If your fish does get an infection, a good antibiotic will be very helpful in aiding their recovery.

A lowered immune system can result in your fish getting an infection, which can cause cloudy eyes as a primary symptom as your fish tries to fight it off.

Infections are more commonly caused by bacteria than parasites, though. In order to try to prevent these, it’s a good idea to ensure everything that goes into your tank has been cleaned thoroughly.

This includes decor, tools, and plants, which may carry harmful bacteria into your tank’s waters.

Parasites and bacteria can be brought into the tank when introducing new fish. This is why we recommend quarantining any new fish you bring home before adding them to a community tank.

Does Cloudy Eye Fish Disease Go Away?

It honestly all depends on the cause and level of damage.

In some cases, as a result of an illness, it may be curable and go away as the illness has been treated with the recommended or prescribed medication. Or if it was trauma to the eye, it may disappear as the eye heals.

In other cases, the cloudy eye may result from cataracts or a parasitic eye infection, which can permanently cause the eye to become cloudy.

Can Cloudy Eyes Kill a Fish?

In the wild, cloudy eyes are likely to cause a fish to die as the fish is unable to see. Their eyes are cloudy or filled with mucus, so they cannot navigate very well, making them extremely vulnerable to predators and parasites.

As a cloudy eye is a symptom of illness or something wrong and not an actual illness in and of itself, it’s best to usually take it as a sign that something more serious is affecting your fish.

It is the illness or infection causing the cloudy eyes that could be deadly to your fish, so whilst cloudy eyes won’t cause your fish to die, whatever the root problem is could definitely lead to your pet’s demise unless you seek appropriate treatment.

Is Cloudy Eye in Fish Contagious?

If you have multiple fish in the same tank with cloudy eyes, you may think there’s a chance that cloudy eyes are contagious.

But this isn’t the case. If multiple fish in the same tank exhibit this issue, it’s likely a symptom of another illness, such as a bacterial infection or parasite, which can be contagious.

Recognizing this early means you’ll be able to seek appropriate treatment faster; therefore, your fish will be more likely to recover from their illness.

Can Cloudy Eyes Be Treated?

The cloudy eye will usually go away of its own accord once its cause has been taken care of.

For example, suppose it is determined that your fish’s infection caused the case of cloudy eyes. Once he has reacted to the medication and begun recovery, the symptom of cloudy eyes should diminish over time.

That being said, if the damage to your fish’s eyes was too bad, it may have caused a permanent issue that cannot be reversed.

If this is the case, moving forward, it’s best to ensure you’re preventing further damage and keeping your fish comfortable.

You can do this by keeping the tank clean and the water parameters in check and ensuring that all decorations with sharp edges are removed from within your tank.

If the cause of the cloudy eyes is cataracts, there may be the option for surgery to help remove the growth. However, antibiotics are usually prescribed to treat infections and/or steroids, which can help reduce inflammation.

All in all, cloudy eyes are a common occurrence in nature and home aquariums and are not an illness but a symptom of something else – something that could be deadly to your fish.

So it goes without saying that if you notice cloudy eye fish problems, you should first look to identify the root cause and begin treating this issue immediately to prevent any permanent damage to the eye.

If unsure, consult with a professional and remember that prevention is always better than treatment. Ensure the upkeep of your tank is top-notch and that your fishy friends are on a cultured fish diet, and you’ll have a better chance of avoiding cloudiness in fish. 

Sharing is caring!

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.