Let’s start a guide on popeye with a story about my friend’s betta fish. Not long ago, a close friend of mine, a pet lover, came to me looking worried. He said, “My betta’s eye looks swollen and bulging out. It wasn’t like this before.” As soon as he described the symptoms, I had a good idea of what was happening.

I told him, “Sounds like your betta might have popeye.”

He looked confused because he’d never heard of it before. So, I sat down and explained what it was, what causes it, and how serious it can be if not treated early. That’s when I realized a lot of fish keepers might not recognize the signs right away.

I put this guide together to help others understand popeye, how to spot it early, and what steps to take to help their betta heal.

What is Popeye

Popeye, also known as exophthalmia, is a condition where one or both of your betta’s eyes bulge or look swollen. It is not immediately fatal but can lead to severe issues if left untreated. It can be treated effectively with the right care.

It usually appears as swelling or a bubble under one or both eyes, which can affect your betta’s vision, health, and overall well-being. Popeye happens when fluid builds up behind the eye, pushing it outward.

Types of Popeye

Unilateral Popeye

If only one eye bulges, it’s usually something external, like an injury. Your betta might’ve bumped into a sharp decoration, got into a fight with a tank mate, or just had a small infection in that eye alone. This is called unilateral popeye, and it’s often less serious if caught early.

Bilateral Popeye

But if both eyes are swollen, that’s called bilateral popeye, which usually means something deeper is going on. It could be a bacterial infection throughout the body, poor water quality, or even internal organ issues.

Causes of Popeye in Betta Fish

It’s not the one factor that causes popeye in betta fish; instead, multiple factors lead to this health issue. Some of the most common causes are:

Poor Water Quality

When your aquarium water contains a high level of ammonia, nitrites, and nitrates, it can weaken the betta’s immune system. These unwanted parameters make the fish susceptible to infections and diseases like popeye. Poor water quality mostly causes bilateral popeye.

Physical Injury

Bettas may exhibit aggressive interactions with sharp decorations or artificial plants. This can injure their eyes and lead to popeye. The injury-related popeye usually affects the one eye.

Infections

This is one of the most severe causes of popeye, which is actually related to poor water quality. Poor water conditions can lead to bacterial and fungal infections, which affect both eyes of the fish, resulting in bilateral popeye. If this is the reason, multiple tank mates will exhibit the symptoms.

Sometimes, an already underlying infection in a fish can cause the disease, in which case only the affected betta will suffer. Infections usually cause swelling, where the inflamed orbital tissue pushes the eyeball outward. Similarly, certain parasites can cause swelling or bulging out of the eyes.

Vitamin Deficiency

A lack of essential vitamins, particularly vitamin A, can contribute to eye health issues.

Symptoms of Popeye

Just as the causes of popeye vary, their symptoms also differ depending on the causes. Recognizing the early signs of popeye is very essential to treat the condition promptly.

• The most apparent symptom is swelling or protruding of one or both eyes
• Cloudy or discolored eyes
• A clear or cloudy bubble forming under the eye
• Redness or inflammation around the eye
• Lethargy and loss of appetite
• Behavioral changes such as hiding or reduced swimming activity as usual in other illnesses
• Loss of eyesight in severe cases

Popeye or Something Else

Many betta owners get confused about this. Popeye can look similar to other eye problems, so here’s how to differentiate.

Popeye vs. Eye Cloud

If the eye is cloudy but not sticking out, it’s probably just an eye cloud, a separate issue usually caused by poor water or a minor infection.

Popeye vs. Cataracts

Cataracts show up as a cloudy lens inside the eye, but again—there is no bulging.

Popeye vs. Injury

A recent injury might temporarily make one eye look swollen, but it usually goes down. Popeye, on the other hand, sticks around and often gets worse.

How to Prevent Popeye in Betta Fish?

It is good to prevent popeye before it occurs rather than treat it afterwards. So why not take preventive measures in advance to avoid suffering your betta from popeye?

• Regular water changes (25-50% weekly) and proper filtration help keep ammonia, nitrites, and nitrates at safe levels.
• Choose smooth decorations and plants that won’t injure your betta’s delicate fins or eyes.
• Feed your betta a well-balanced diet with high-quality pellets and frozen or live foods rich in essential vitamins.
• Always quarantine new tank additions to prevent introducing infections or parasites.
• If your betta is in a community tank, ensure that tank mates are peaceful and not causing stress or injuries.

Treatment of Popeye

Detected the early signs of popeye in your betta fish, and still waiting for mercy? Hurry up, and begin its treatment in the best possible way. We have passed many bettas through our proven treating process and it has helped us in successful recovery of several bettas.

Safe and Low-Risk Treatment Methods

Maintain Clean Water

If your main tank has poor water quality, it’s best to move the fish to a quarantine tank, as this will help with a more focused treatment without further degrading their condition. Maintain stable water chemistry and proper betta fish water temperature including pH, GH, and KH.

To achieve this, pass the tap water through a water conditioner. Regularly check the ammonia, nitrite, and nitrate levels. Keep nitrate within an acceptable range of 0-10 ppm while keeping the levels of the other two as close to zero as possible.

We generally use Seachem Prime to detoxify the ammonia and nitrite levels. Don’t keep sharp decorations in your hospital tank, and remove them from the main tank if there are any.

Add Natural Remedies

If the popeye is caused by a bacterial infection, add Catappa (Indian Almond) leaves to the tank. These leaves have antibacterial properties that can help your betta heal. One large leaf is enough to achieve the desired goal and avoid drastic pH changes. We also sometimes use a small dose (1/4 cap) of Stress Guard to reduce stress and promote healing.

Aquarium Salt Treatment (With Caution for Planted Tanks)

Popeye often results from fluid buildup, and Epsom Salt (Magnesium Sulfate) can provide temporary relief by reducing fluid retention.

Arrange a separate container and mix 1 tablespoon or 3-4 teaspoons per 10 gallons of tank water. If you have a low setup, especially with small betta fish tanks, use 1 teaspoon per two gallons of water. Give your betta a salt bath for 10-15 minutes before returning it to the main tank. If you fear the salt’s effects worsening, dilute the solution after keeping the betta in it for 5 minutes. Repeat daily or every other day for about a week.

If you can arrange a separate container, don’t use Epsom Salt in the main tank. However, if it’s the only way to mix it in the main tank, then use half of the prescribed dosage, as too much salt can adversely affect live plants and invertebrates like snails.

High-Risk Treatment Methods

If your betta has recovered using safe and low-risk methods, congratulations! If not, don’t worry—prepare to treat your betta with medications.

Treating Popeye from Infection (Bilateral Popeye)

If popeye is bacterial, there are more chances that you will eventually need to resort to medications. The recommended medications are broad-spectrum antibiotics like Seachem Kanaplex (Kanamycin) or Erythromycin. Medications like API Fin and Body Cure (Doxycycline) or Mardel Maracyn 2 (Minocycline) are also recommended.

We, and most pet vets, prefer to administer the antibiotics by mixing them into the food. Here’s our simple recipe:

• 1 tablespoon of food (thawed frozen food or softened pellets/flakes)
• 1/16 tsp of antibiotic powder, i.e., Kanaplex
• A small amount of melted gelatin (to bind the mixture). Or mix it with Seachem Focus for better absorption.
• Refrigerate or freeze the mixture until ready to use.
• Add garlic extract if betta refuses to eat.

Repeat this process for 3-4 days. If your betta does not seem to have recovered, switch to Erythromycin and follow the same process of mixing it with food.

If you’re administering the antibiotics by mixing them with water, do regular water changes after adding the medications to the water. Add another dose when you perform 90% of the water change.

Avoid These Medications

Metronidazole: Primarily effective against anaerobic bacteria, which are uncommon in aquariums.

Praziquantel: An antiparasitic that does not treat bacterial infections.

Frequently Asked Questions (FAQs)