Betta Cloudy Eye 101(Symptoms Pictures & Proven Treatment)

Cloudy eye in betta fish is quite common. Luckily, it is easily prevented and treatable with broad spectrum antibiotics and good supportive care.

However, this condition requires immediate attention. When left untreated, your betta fish will lose its eyesight or possibly die.

Like other common eye disorders in fish, the cloudy eye has several potential causes; some are more deadly and contagious than others.

This article deals with the most common causes, symptoms, and treatment options of betta cloudy eye.

What is Betta Fish Cloudy Eye?

why is my bettas eye cloudy

Fish cloudy eye, or corneal opacity, is a condition in which the cornea becomes irritated or inflamed. It may result in an excessive fluid buildup (edema) in one eye or both eyes, causing it to look whitish or slightly opaque

Affected betta fish may exhibit one or more clinical signs of other eye disorders, like popped out, hemorrhages in or around the eye, swelling, and ulcerations.

Several different conditions can contribute to the betta cloudy eye, including ammonia burn, bacterial infection, internal parasites, cataracts, or injury. Correctly diagnosing this disease is important to ensure the best possible treatment.

The Symptoms of Cloudy Eye in Bettas

The most notable symptom of the betta fish’s cloudy eye is the one that has given it its name – an opaque whitish film that covers your betta’s eye. 

Depending on the underlying cause of infections, injury and/or eye malfunction, the betta fish may show other physical symptoms as well.

TraumaFrayed fins
Clamped fin
Missing scales
Damaged eyes
Hiding more than usual
Loss of appetite
Ammonia BurnGasp for breath at the top of the water surface
Purple or red gills
Rapid gill movement
Cloudy eyes
Red streaks on the body and fins
Lethargic and loss of appetite
Laying on the tank bottom
Bacterial InfectionPop-eye
Cloudy eye
Hemorrhages in or around the eye
Milky or shedding slime
Abnormal swimming behavior
Increased respiratory effort
‘Fungus’ on the gill plate, base of the fins occasionally
CataractsIntraoribital condition occurs within the orbit of the eye
The lens becomes opaque (often gray)
The lens doesn’t transmit light efficiently

Internal Parasites

Internal flagellates, especially Spironucleus spp., are most likely to infect young betta fish or fry. Once infested, your betta fish may display the following symptoms:

Disease Symptoms
Hole In The Head Disease Moldy lesions on the head and lateral line (HITH or HLLE)
Cloudy eye
White, stringy feces
Subdued coloration
Loss of appetite
Body and Gill FlukesMissing scales and red spots on the skin
Loss of color
Cloudy eye
Excess mucus secretion on gills or body
Scratching against objects by the affected betta fish
Gills moving rapidly
Flashing behavior
Decreased appetite

Causes of Betta Cloudy Eye

As you see, there are various reasons why a cloudy eye(s) can form, and sometimes the true underlying cause can be hard to determine.

Common causes of betta cloudy eye are ammonia burns, bacterial infections, internal parasites, and injury. Poor water quality is often the root cause of betta cloudy eye.

Often, if only one eye is affected, it is most likely that the betta fish experienced some sort of bacterial eye infection caused by trauma or injury. In bettas, this can be caused by anything from rubbing against abrasive aquarium décor or fighting with another betta.

When both eyes are affected in a well-seasoned or cycled tank, a more serious bacterial infection or parasites are responsible in most cases.

Ammonia poisoning or burns typically happen when setting up a new tank. Elevated unionized ammonia (NH3) level is no joke and will kill your fish fast if not addressed promptly. Further Reading: Betta Ammonia Poisoning: Causes, Symptoms & Treatment


Your betta fish has a better chance of a full recovery if the underlying cause is correctly identified, and the treatment is performed in a timely manner.


Cataracts in fish

Less common in fish, but cataracts can cause betta fish cloudy eye. It’s more commonly seen in older bettas with many factors, including genetics and diet.

Cataracts occur when the lens becomes opaque (often gray) and does not transmit light efficiently, causing vision impairment. There’s no treatment for cataracts in betta fish.

Ammonia Poisoning

ammonia poisoning symptoms

Bettas are among the popular beginner fish; New aquarium keepers may feel eager to add fish, but unfortunately the failure to cycle a new tank properly is a common mistake that can lead to betta ammonia poisoning.

Other Potential Causes Include Combinations Of:

  • Bacteria buildup
  • Chlorinated water
  • The decomposition of organic matter
  • Overpopulation (Fish or/and shrimps, snails)
  • Overfeed


  • Use an ammonia test kit to test the ammonia level in your tank;
  • If it’s above 0.1 ppm, perform a 25% to 50% water change over a few days, and make sure the water added is at the same temperature as the aquarium.
  • Ammonia-lowering chemicals can be added to the tank in severe cases.
  • Increase aeration and filtration with a good filter and air stone.
  • Reducing feeding will help by lowering the amount of waste.

Internal parasites

Parasites that affect the eyes of both freshwater and marine fishes are quite common. There are many different types of parasites, but the cloudy eye in fish is often associated with internal parasites.

Spironucleus spp. (Hexamita)

Hexamita in betta fish

Spironucleus spp. (Hexamita), also known as hole-in-the-head disease, are flagellated protistan parasites that most frequently occur in the intestinal tract of fish [1].

Once infested, your betta fish may produce white stringy poop, and the fish may lose their appetite and become more subdued than normal. Their white, stringy feces can be confused for parasitic flatworms. The lesions are seen on the betta fish’s head or flanks. 

Trematodes (Flukes)

Gyrodactylids in betta fish
Gyrodactylids in betta fish

You may have heard of something called Flukes in fish. They are actually referred to many species of trematodes that only live internally in their host.

Gyrodactylids and ancyrocephalids are the two most common monogeneans in freshwater fish. The former gives birth to live young and is usually found on the skin and eyes, while the latter lays eggs and infects the gills.


Metronidazole has been found to be an effective treatment for internal, single-cell parasites, but it should be given through medicated fish food. If your betta fish is refusing to eat, Metronidazole can also be administered as a bath. 

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Author notes: Metronidazole is most effective when combined with Praziquantel in medicated fish food.

Bacterial Infection

As we mentioned in this article, the majority of bacteria that cause disease in betta fish are gram-negative, but contrary to popular belief, most disorders of the eye in fish are gram-positive.

These infections are generally caused by Streptococcus and several other closely related groups, including Lactococcus, Enterococcus, and Vagococcus [2]. Understanding this fact is crucial when choosing the appropriate treatment.


Erythromycin, an effective anti-Gram-positive antibiotic for streptococcus infections, has proven to be quite effective when used in a medicated food mix. Be aware erythromycin can permanently wipe out your tank’s nitrifying bacteria in the biofilter, so having a spare sponge filter to replace during the treatment is very important.

Recommended product: API® E.M. Erythromycin

How to Prevent Cloudy Eye in Betta Fish?

Marble betta

One of the main ways to prevent cloudy eye disorder is maintaining the water quality and ensuring it remains healthy and stable. When the water quality is kept at the proper levels, 0 ppm for nitrite and ammonia, and 20 ppm for nitrates, your betta will be safe from the cloudy eye. To ensure this happens, follow the steps below.

A Regular Water Change

Regularly changing your tank’s water will keep the water quality at healthy levels. For smaller tanks, the water changes need to be larger and more frequent. Whereas, for larger tanks, you will only need to perform a 25% water change each week. 

Clean It Up

Maintain a clean tank. If you have a substrate, you should vacuum it regularly to remove feces and leftover food. Routinely clean the tank’s ornaments, including any silk plants.

Betta Fish Filter

A proper filtration system is a must for betta fish tanks. A betta filter should be able to process the water in your tank with adequate filtration rate and circulation. Change out the filter cartridges as needed.

Do not overstock your tank.

Overstocking betta fish tanks can lead to waste accumulation, eventually leading to poor water quality. 

Tanks smaller than 15 gallons will compromise your betta’s health. They can survive in the smaller tanks but will not remain healthy.

Quarantine All New Additions

Placing new fish or other tank additions, including plants and ornaments, into a separate quarantine tank for two weeks is essential to ensure there are no diseases or parasites the betta can be infected with.

Is Betta Fish Cloudy Eye Contagious?

Depending on the cause of the cloudy eye, betta cloudy eye can be contagious to other bettas. If parasites or bacterial infections cause betta cloudy eye, then it is contagious as long as the life cycle of the parasite or bacteria is not broken.

Is Cloudy Eye Fatal to Bettas?

Any illness that goes untreated in your betta fish can potentially prove to be fatal, although the cloudy eye is least likely to cause death. Your Betta will quickly recover as long as you adjust the water’s quality levels and treat your Betta fish. 

However, if the symptoms worsen or additional symptoms occur, there may not be a cloudy eye, and you will need to start investigating further. You can get a diagnosis if necessary, from your local aquatic center if this is the case. 


With rapid detection and action, cloudy eye betta is easily treated and should not prove fatal. Regular tank maintenance is a must for keeping the water quality at a healthy and safe level. 

Keep in mind that prevention is better than a cure. Be sure to quarantine any new betta or tank additions and regularly test your tank’s water to ensure it remains healthy. 

Good luck!

Article Sources:

  1. Parasitic Diseases of Fish [MerckvVetManual]
  2. Streptococcus, Eye Infections in Fish [Aquarium Pond Answers]
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2 thoughts on “Betta Cloudy Eye 101(Symptoms Pictures & Proven Treatment)”

  1. Thanks for the ‘cloudy eye’ advice.
    I’ve been treating her with kanaplex but yesterday the cloudy eyes appeared. I added aquarium salt to her quarantine tank and I see her eyes this morning. Now….i just need for her to eat.

  2. I wonder how long after treating my aquarium with aquarium salt will the cloudy eye in my beta go away I just got her put her my tank in realized she had it aquarium salt and as soon as I noticed just wondering if I should see a change within a day or two or how long I’ve never had this happen with any of my bettas


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