Cloudy Eye Fish Disease: Signs, Causes & Treatment

Blue betta fish with cloudy eye disease in a tank
Image credit: lightofapiscesmoon / Instagram

Noticing your fish’s eyes turning opaque, milky, or cloudy could be alarming and distressing. Although cloudy eye is a common condition for fish, it is something that should not be taken lightly,

A cloudy eye in fish is usually a symptom rather than the disease itself. It can be caused by bacterial, fungal, and parasitic infection, physical injury, dietary issues, poor water quality, and aging.

Pin-pointing the causes is the first step in treating this condition. This guide will walk you through what you need to know about cloudy eyes in fish, from diagnosing the cause to the possible treatments.

What Is Cloudy Eye in Fish?

Upward swimming betta fish with cloudy eyes
Image credit: lightofapiscesmoon / Instagram

Cloudy eye in fish is a condition where a fish’s eye appears opaque or milky. It’s usually a symptom of another problem rather than a disease itself.

Several factors, including poor water quality, bacterial infections, fungal growth, or injury, can cause this condition.

When a fish has cloudy eyes, its vision may be impaired. This can make it difficult for the fish to find food, navigate, or avoid other aggressive tank mates.

If left untreated, the condition can lead to blindness or further health issues. Therefore, fish owners must notice and address this symptom quickly.

Accurately diagnosing the exact cause is essential to treat the condition effectively. Sometimes, a simple adjustment in diet or environment can resolve the issue, but in other cases, medication and vet examination may be required.

Signs and Symptoms of Cloudy Eye Fish

A cloudy eye in fish is easy to spot: the usually clear eyes appear cloudy, milky, opaque, or foggy. It’s a common sign that something’s off, whether it’s the water quality, an infection, or an injury.

Fish with cloudy eyes might bump into things more often because their sight is affected.

The condition might be in one or both eyes and can come with other worrying signs. You might notice your fish acting strangely, like rubbing against tank objects, losing appetite, or their colors might fade.

These symptoms call for a closer look to determine what’s causing the condition.

What Causes Cloudy Eyes in Fish?

Dark colored betta fish with a visible cloudy eye
Image credit: niicholemulder / Instagram

Various factors and conditions can cause cloudy eyes in fish. You need to diagnose the condition’s specific cause to provide proper treatment.

Here are some causes of cloudy eyes in fish with their diagnosis and treatment:

1. Bacterial Infections

Bacterial infections in fish, notably those caused by Streptococcus iniae and Aeromonas hydrophila, are a common reason behind the development of cloudy eyes.

These bacteria can aggressively infect the eye, leading to symptoms like a milky or foggy appearance, swelling, and, in severe cases, a pronounced bulging of the eye known as “pop eye.”

Diagnosing the Cause

Diagnosing these bacterial infections involves closely observing the fish for symptoms such as swelling and redness of the eyes besides cloudiness.

Additional signs might include abnormal swimming, hemorrhages near the eye, or a milky slime covering the body. Vet examinations should be conducted to identify the bacteria that cause cloudy eyes accurately.

Treatment Options

Effective treatment generally involves antibiotics, with choices depending on whether the bacteria are gram-positive or gram-negative.

Knowing whether a bacteria is gram-positive or gram-negative is crucial because each type responds to different antibiotics. Hence, asking for a veterinarian’s advice and diagnosis is a must.

Careful water quality and tank hygiene adjustments are also crucial to support the treatment and prevent reinfection. It’s also important to isolate affected fish during treatment to contain the spread of the infection.

To keep my fish safe, I always ensure that my isolation tank is ready. Besides the tank, I also have a spare functional filtration system, thermometer, heater, and decorations used solely for the isolation tank.

By ensuring that these items are always at my disposal, I can quickly isolate and treat my infected fish, making the process less stressful.

Pro Tip: In filling the isolation tank, you can use as much water as you can spare from your other active tanks (not the tank where your infected fish originated). This ensures that the water is already cycled and contains beneficial bacteria, which is crucial for the fish’s health.

Watch this video to learn more about how to quarantine a fish:

Quarantine Your Fish - Why, How, and When To Medicate

2. Fungal Infections

Fungal infections, such as those caused by Saprolegnia or Ichthyophonus hoferi, often emerge when fish are most vulnerable — due to injury, stress, or suboptimal living conditions like poor water quality or overcrowded tanks.

Visible signs include cotton-like growths on the fish’s body, including the eyes, and if left untreated, can lead to more severe complications like septicemia or fin rot.

Fungal infections often occur in tanks with substandard water quality, poor oxygenation, or high ammonia levels.

Stress factors such as low water temperature, lack of aeration, or overcrowded tanks also contribute to the vulnerability of fish to fungal infections.

Diagnosing the Cause

To determine if a fungal infection is behind a fish’s cloudy eye, look for accompanying signs like white or grey fuzzy patches on the eye or body. These growths can resemble cotton and are not typically seen with bacterial infections.

A definitive diagnosis often requires a vet’s examination of the affected tissue. Water quality tests are also crucial, as poor conditions commonly contribute to fungal outbreaks.

If these signs are present and water quality is poor, a fungal cause is likely.

Treatment Options

Treatment of fungal infections generally includes medicating the water with substances like potassium permanganate, especially for Saprolegnia. For Ichthyophonus hoferi, raising salt levels and water temperature may be effective.

Maintaining good water quality, proper aeration, and appropriate tank temperature are essential preventive measures.

3. Parasitic Infections

Parasitic infections in fish can lead to various symptoms, including cloudy or milky eyes.

These infections are typically caused by parasites that invade the eye or the surrounding tissues, such as flukes or protozoa, which can be introduced into an aquarium through new fish, plants, or even replacement water.

Diagnosing the Cause

A fish with a parasitic eye infection may show other signs of distress, including abnormal swimming, inflammation, and visible parasites on the eye, which can be dangerous for the fish if not promptly addressed.

You should also consider the fish’s history, whether you have recent additions to the tank that might have introduced parasites.

Veterinary consultation is necessary since specialized equipment is needed to identify the parasites that have infected your fish.

Treatment Options

Treating parasitic infections that cause cloudy eyes generally involves anti-parasitic compounds like praziquantel for flukes and metronidazole for protozoan infections.

The treatment plan may include administering medication directly into the water or via food if the fish are still eating.

Complete eradication of parasites requires following a strict medication schedule, which may involve increasing the water temperature to speed up the life cycle of the parasites, making them more susceptible to treatment.

Improving tank conditions and conducting regular water changes are vital to aid recovery and prevent future infections.

4. Physical Injury

Physical injuries are also common causes of cloudy eyes in fish. Such injuries can occur when fish collide with sharp tank decorations or are handled roughly.

The absence of eyelids in fish means their eyes are more exposed and susceptible to injury.

Without the protection eyelids provide, fish can easily suffer from physical abrasions caused by tank decorations, substrate, or aggressive behavior from other fish.

This vulnerability can contribute to the development of cloudy eyes, as the exposed tissues are more prone to damage and subsequent infection or inflammation.

Diagnosing the Cause

In diagnosing whether the cloudy eyes of your fish are caused by trauma or physical injury, check for signs of damage to the fish’s body or fins.

If a collision or fight causes trauma, injuries in other parts of the body could also be present. Usually, only one eye is also affected. The area around the cloudy eye may also have visible signs of wounds or abrasion.

Treatment Options

The primary treatment for physical injuries is to provide a clean and safe environment to prevent infection. This includes removing sharp objects from the tank and ensuring optimal water quality.

Sometimes, a mild antiseptic may be used to prevent secondary bacterial infections.

5. Poor Water Quality

Poor water quality is a prevalent cause of cloudy eyes in fish. High levels of toxins like ammonia, nitrites, and nitrates can irritate a fish’s eyes, leading to cloudiness. Such conditions stem from overfeeding, overcrowding, or inadequate filtration.

Poor water quality also lowers your fish’s immune system, making it susceptible to bacterial and fungal infections.

Diagnosing the Cause

You need to conduct a water quality check to see if poor water quality causes cloudy eyes in your fish. Testing the water for ammonia, nitrite, and nitrate levels will help determine if the cloudiness is due to a toxic environment.

Also, watch your fish’s behavior — if they seem less active or are gasping at the surface, your water might be the problem.

Treatment Options

Improving water quality involves regular water changes, proper tank maintenance, and ensuring the filtration system functions correctly.

It may also require reducing the number of fish or the amount of food given if overstocking or overfeeding is an issue.

To ensure the water quality in my tanks is safe for my fish, I conduct bi-weekly water changes where I replace 25% of the aquarium water with treated water.

Completely replacing the aquarium water isn’t advised because it will remove the beneficial microorganisms and disrupt the nitrogen cycle in the tank, which could be harmful to your fish.

6. Nutritional Deficiencies

Cloudy eyes can also be a symptom of a poor diet, leading to a weakened immune system.

Like humans, fish need a balanced diet of various nutrients to stay healthy. When fish don’t get the right vitamins and minerals, they can develop cloudy eyes.

Diagnosing the Cause

Cloudy eyes caused by poor diet and nutritional deficiency are usually accompanied by other signs and symptoms, such as lethargy, fading colors, and stunted growth.

Treatment Options

Addressing cloudy eyes caused by nutritional deficiency requires a varied diet that meets all their dietary needs.

This could include high-quality flakes, pellets, frozen or live foods, and vegetable supplements. Targeted supplements may be recommended for specific deficiencies to address the lack of certain nutrients.

7. Aging

As fish age, they can experience a natural decline in their vision, which may manifest as cloudy eyes.

Over time, older fish may also develop cataracts, a condition characterized by the clouding of the lens in the eye, which can result in an opaque appearance.

Diagnosing the Cause

You can determine if the cloudy eyes of your fish are caused by aging by observing age-related changes, such as the decrease in activity, change in color, and development of cataracts.

Signs of cataracts can include a noticeable whitening or clouding of the lens inside the fish’s eye, leading to a milky or opaque appearance.

Fish with cloudy eyes caused by aging and cataracts will have difficulty swimming and navigating, often bumping into objects inside the aquarium.

Treatment Options

There’s no cure for age-related cloudiness and cataracts, but supportive care can make your fish comfortable.

This includes maintaining pristine water conditions and providing an easy-to-navigate tank layout. It’s also helpful to offer high-quality food that caters to the nutritional needs of older fish.

How to Prevent Cloudy Eye Fish Disease

Betta fish showing signs of cloudy eye disease near the tank wall
Image credit: lightofapiscesmoon / Instagram

Preventing cloudy eye disease in fish involves a multi-faceted approach focused on maintaining optimal aquarium conditions, providing proper nutrition, and ensuring good tank management practices.

Here’s how to minimize the risk of this condition:

  • Maintain Water Quality: The most effective preventive measure is keeping the aquarium water clean. Regularly test and adjust the water parameters to ensure they are within safe limits for ammonia, nitrite, nitrate, pH, and temperature.
  • Proper Nutrition: Feed your fish a balanced diet rich in essential nutrients. A mix of high-quality dry, frozen, and live foods ensures they receive a range of vitamins and minerals. Avoid overfeeding as it contributes to poor water quality and can directly stress the fish.
  • Tank Management: Avoid overcrowding your tank, as this can lead to stress and poor water quality, weakening a fish’s immune system. Ensure that the tank is properly aerated and that the filtration system is adequate for the tank’s size and population.
  • Regular Observation: Keep a close eye on your fish for signs of distress or disease. Early detection of changes in behavior or appearance can allow for prompt action to address any issues before they lead to cloudy eye disease.
  • Quarantine New Additions: Always quarantine new fish before introducing them to your main tank. This can prevent the spread of pathogens and parasites that may cause cloudy eye disease. A quarantine period of at least two to four weeks is recommended.
  • Stress Reduction: Create a tank environment that reduces stress for the fish. This includes providing hiding places, maintaining a consistent light cycle, and avoiding sudden changes in the tank environment.
  • Veterinary Care: For species prone to eye issues or in tanks where problems persist, consulting with a veterinarian specializing in fish health can provide targeted advice and care.

Following these guidelines can significantly reduce the risk of your fish developing cloudy eye disease.

Remember that prevention is always better than cure, and a proactive approach to aquarium care is the best way to ensure the health and well-being of your aquatic pets.

Does Cloudy Eye Go Away on Its Own?

It largely depends on the cause of the condition. Cloudy eye in fish sometimes clears up without treatment, especially if it’s caused by minor irritations or stress.

If the underlying issue is addressed, such as improving water quality or diet, the cloudiness can be resolved as the fish’s health improves.

However, medical intervention is usually required to treat the condition effectively in cases of bacterial infections, injuries, or serious nutritional deficiencies.

Is Cloudy Eye in Fish Contagious?

Betta fish with a cloudy eye swimming by a tank thermometer
Image credit: lightofapiscesmoon / Instagram

Cloudy eye in fish isn’t typically contagious because it’s usually a symptom rather than a disease. It will not pass from fish to fish if it’s due to poor water conditions or injury.

But if bacterial infections or parasites cause it, cloudy eyes can spread to other fish in the tank. That’s why figuring out what’s causing the condition is essential.

Good tank hygiene and regular water testing can prevent many conditions that lead to cloudy eyes. If there’s an outbreak, separate the affected fish and clean the tank to protect the other inhabitants.

Can Cloudy Eye Kill a Fish?

A cloudy eye isn’t usually deadly to fish, but it can signal underlying health issues that could be serious. If caused by infections, injuries, or poor care and left untreated, these problems can lead to a fish’s death.

It’s crucial to address the root causes of cloudy eyes to prevent potentially fatal complications.

As established, determining the root cause of cloudy eyes in fish is crucial in treating and managing the condition. If you have questions or other helpful care tips about cloudy fish eyes, comment below!

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