What is Popeye Betta Fish? Causes, Symptoms, and Treatment

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By Linh Nguyen Updated on 02 Feb 2023

Popeye in Betta fish is a condition that you'll want to be aware of and know how to treat. Popeye in betta fish is a condition caused by a bacterial or viral infection. The most common symptom is bulging eyes. Other symptoms include cloudy eyes, swollen gills, and lethargy. Treatment for popeye usually involves antibiotics or antiviral medications. This disease is completely preventable by maintaining good water quality and quarantine procedures.

If you're a Betta fish owner, it's important to learn about Popeye so that you can be prepared if your fish ever contracts the illness. Let's take a look at what this disease is and what you can do to help your fish if he or it becomes infected.

One eye of betta fish affected by popeye disease

One eye of betta fish affected by popeye disease

1. What is popeye betta fish?

Popeye betta fish is a term used to describe a betta fish that has one or both eyes bulging outwards. This condition is also known as exophthalmia. The cause of popeye is usually unknown, but it can be caused by a bacterial or viral infection, physical injury, or a parasite. There are three different types of popeye: exophthalmia (when only one eye is affected), orbital edema (when both eyes are swollen), and anterior uveitis (when the front part of the eye is inflamed). 

If you notice that your betta fish's eye or eyes are bulging out, you must find the cause and treat it immediately. With prompt treatment, most bettas make a full recovery and go on to live happy and healthy lives. In most cases, popeye can be successfully treated with a combination of antibiotics and anti-parasitic medications, but if the underlying cause is not resolved, the condition may recur. In severe cases, surgery may be necessary to remove the affected eye (s). However, if the condition is left untreated, it can eventually lead to blindness.

2. Causes

Popeye can be caused by a number of different things, including bacterial infections, physical trauma, and even certain types of parasites. While popeye is usually not fatal, it can cause your betta fish a great deal of discomfort and may even lead to blindness if left untreated. Below are details of the most common causes of popeye disease in bettas.

2.1. Poor water quality

Water quality is extremely important to the health of betta fish, and poor water quality can lead to a number of health problems, including popeye disease. Popeye disease is caused by a bacterial infection that enters the fish's body through the eyes. The bacteria can cause the fish's eyes to swell and bulge, and eventually, the fish may go blind. Poor water quality can also cause other health problems, such as fin rot and skin diseases.

There are a number of different causes of poor water quality, but one of the most common is overstocking. When there are too many fish in a tank, the water quality can deteriorate quickly. This is because the fish produce a lot of waste, which can pollute the water. Another common cause of poor water quality is using tap water that contains chlorine or other chemicals. These chemicals can be harmful to fish and can cause a number of health problems.

2.2. Infection

There are many different types of infections that can cause popeye disease in bettas, but the most common culprit is bacteria. Bacterial infections are often the result of exposure to contaminated water and can cause the tissues around the eye to become inflamed and swollen. In severe cases, the infection may spread to other parts of the body, causing additional damage and making the fish even sicker. If not treated promptly and properly, a bacterial infection can be fatal to a betta.

Popeye disease can also be caused by viruses, although this is much less common than bacterial infections. These viruses are usually spread through contact with other infected fish. They can enter the body through the gills, skin, or mouth and begin to multiply. As they do, they release toxins that damage the tissues around them and cause the inflammation and swelling associated with Popeye.

Viral infections are often more serious and can cause more widespread damage to the body, including the eyes. If not treated promptly and properly, a viral infection can be fatal to a betta.

2.3. Injury

One of the most common causes of popeye in betta fish is injury. When a betta fish is injured, oftentimes there is damage to the eye itself. This can cause the eye to become swollen and inflamed, which can eventually lead to a popeye. In addition, when a betta fish is injured, it is more likely to develop an infection. If this infection spreads to the eye, it can also cause a popeye. In some cases, Popeye may be caused by a foreign object that has become lodged in the eye. This can happen if the fish rubs its eye on something sharp or abrasive.

Treatment for popeye caused by injury typically involves antibiotics to clear any infection and anti-inflammatory medication to reduce swelling. In severe cases, surgery may be necessary to repair damage to the eye.

2.4. Nutritional deficiency

A common cause of popeye in betta fish is nutritional deficiency. This can be caused by a number of factors, including inadequate diet, poor water quality, and lack of vitamins and minerals in the water.

Popeye is often the result of a vitamin A deficiency. Vitamin A is essential for healthy eyesight, and a lack of it can lead to the formation of cataracts. It can also cause inflammation and swelling of the eye tissue, which is what causes the "popeye" appearance.

An inadequate diet is one of the most common causes of vitamin A deficiency in bettas. Many commercial fish foods do not contain enough vitamin A, and some even contain none at all. Bettas require a diet that is high in protein and fat and low in carbohydrates. A good diet for bettas should also contain plenty of vitamins and minerals, including vitamin A.

Poor water quality can also contribute to nutritional deficiencies in bettas. Tap water often contains high levels of chlorine, which can deplete the water of vitamins and minerals. Ammonia and nitrites are also common in tap water, and these can be toxic to bettas. It is important to use a good quality water filter to remove these contaminants from the water before adding it to the aquarium.

Finally, some Bettas are simply unable to absorb nutrients from their food properly due to a genetic defect. This is relatively rare, but it can happen.

2.5. Parasites

Popeye disease in bettas is most commonly caused by parasites. These tiny creatures can invade the fish's body and start to multiply, causing a range of problems including Popeye. 

The most common type of parasite is the protozoan, which is a single-celled creature that can live inside your fish and feed off of its blood. Protozoans can enter your fish through their gills or skin, and they can also be transmitted through contaminated food or water.

Another type of parasite that can cause Popeye is the flagellate, which is a worm-like creature that burrows into your fish's flesh and feeds off of its blood. Flagellates can also be transmitted through contaminated food or water, and they can sometimes be seen swimming in your fish's tank.

a betta fish with a mild stage of popeye disease

3. Symptoms

There are three types of popeye in betta fish: exophthalmia, orbital edema, and anterior uveitis. 

3.1. Exophthalmia - when only one eye is affected

If your betta fish only has one bulging eye, this is a condition known as exophthalmia. Betta fish that are suffering from exophthalmos will often have red, irritated eyes. In extreme cases, the betta's eyeballs may actually protrude out of their sockets. Other symptoms include cloudy vision, excessive tearing, and light sensitivity. The fish may also have trouble swimming and eating.

This can be caused by a bacterial infection, physical trauma, or even irritation from poor water quality. Regardless of the cause, popeye is a serious condition that can lead to blindness and even death if left untreated.

3.2. Orbital edema - when both eyes are swollen

When both eyes are swollen, it is called orbital edema. This is a serious condition and can lead to blindness if not treated immediately. Symptoms include pain and pressure in the eyes, blurred vision, and difficulty moving the eyes. The swelling is caused by fluid buildup in the tissues around the eyes. In severe cases, the fish may be unable to close its eyes properly, which can lead to damage to the cornea, and the eye may bulge out of the socket.

This condition is most often caused by an infection, but can also be a result of physical trauma or an underlying medical condition. Treatment will vary depending on the cause but may include antibiotics or surgery.

3.3. Anterior uveitis: When the front part of the eye is inflamed

Anterior uveitis is a condition that results in inflammation of the front part of the eye. Betta fish with this disease typically exhibit one or more of the following symptoms: redness and swelling in the eye, cloudy or opaque cornea, increased sensitivity to light, and/or a bulging eye.

In severe cases, the fish may also develop ulcers on the cornea. Betta fish may also experience complete vision loss in the affected eye. Left untreated, anterior uveitis can permanently damage the eye and lead to blindness. Treatment for this condition typically involves using topical steroids to reduce inflammation.

a betta fish with severe popeye disease

4. Treatment

There are a few methods that can be used to treat popeye disease in betta fish. One is to increase the water quality by performing regular water changes and using a good filter. Another is to add Epsom salt to the water. Finally, you can use an antibiotic such as erythromycin to treat the infection. Popeye disease is usually not fatal, but it can make your betta fish uncomfortable, so it is important to treat it as soon as possible.

Here are the details on how to do it.

4.1. Using Epsom salt

In case your betta has only one eye swelling, also known as exophthalmia, you can use Epsom salt to treat it.

Epsom salt is a type of magnesium sulfate that can help reduce swelling and inflammation. It's also thought to help boost the immune system, which can be important in fighting off infection. This treating popeye is relatively simple and can be done with common household items. 

To treat your betta's popeye with Epsom salt, add two tablespoons of salt to every gallon of water in your fish tank. You'll need to do a partial water change every day to keep the levels of salt consistent. After a few days, you should start to see the swelling go down and your betta's eyes return to normal. If the condition does not improve or gets worse, you need to review the cause of the disease for more appropriate treatment.

4.2. Using antibiotic

If your betta has popeye in both eyes, it is important to treat both eyes even if one appears to be worse than the other. Failure to do so could result in the disease recurring.

Erythromycin is an antibiotic that can be used to treat popeye disease in bettas. The recommended dosage is 5-10mg/L, and it should be administered orally using a syringe or eyedropper. Erythromycin can be purchased at most pet stores or online retailers.

To administer erythromycin, first, fill a syringe or eyedropper with the appropriate amount of medicine. Then, gently hold your betta in one hand and apply the medication to the affected eye(s) using the other hand. Be careful not to touch the tip of the syringe or eyedropper with anything, as this could contaminate the medication. Repeat this process once daily for 5-7 days, or as directed by your veterinarian.

Erythromycin is generally safe and effective, but side effects can occur. These may include diarrhea and appetite loss. If you notice any of these side effects, stop administering erythromycin and contact your veterinarian right away. With proper treatment, most bettas make a full recovery from popeye disease.

5. Prevent popeye in betta fish

Popeye is a disease that can affect betta fish. It is caused by a bacterial infection and can be fatal if left untreated. There are several things that you can do to prevent your betta from getting popeye. 

  • First, make sure to keep your betta's tank clean. Regular water changes and cleaning of the gravel will help to remove any bacteria that could cause an infection.
  • Second, do not overfeed your betta. An overweight fish is more likely to develop health problems, including popeye. 
  • Third, provide your betta with plenty of hiding places in its tank. A stressed fish is more susceptible to disease.
  • Fourth, avoid using tap water to fill your betta's tank. Tap water often contains chemicals that can be harmful to fish. If you must use tap water, be sure to let it sit for 24 hours before adding it to the tank. This will allow the chemicals to dissipate. 
  • Fifth, quarantine any new fish that you add to your betta's tank. New fish can bring in diseases that your betta may not have immunity to.
  • Sixth, treat your betta's tank with a quality anti-bacterial solution on a regular basis. This will help to kill any bacteria that could cause an infection. 

By following these simple tips, you can help to prevent your betta from getting popeye or any other disease.


That’s all for now on popeye in bettas. If you have any questions or concerns, please let me know in the comments below and I will get back to you as soon as possible. Alternatively, you can also contact me through my website at bettafishpedia.com. Once again, thanks for reading, and be sure to check back for more informative articles about betta fish care.

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