Popeye in Betta Fish: Prevention, Treatment, and Symptoms

popeye in betta fish
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Although betta fish is a low-maintenance fish breed, they have a delicate structure that makes them prone to certain illnesses and injuries.

They could contract a disease or suffer from an injury, no matter how safe their aquarium is.

One of the common health conditions in betta fish is popeye (pop-eye, not The Sailor Man).

You might panic if your betta fish develops popeye, but the good news is that it’s a treatable and preventable condition.

Also, the chances of misdiagnosing popeye and death of betta fish from this condition are low.

So, keep reading this article towards the end as it holds essential information about popeye, such as its causes, symptoms, treatments, and prevention.

What is popeye in betta fish?

Popeyes refers to a condition when betta fish have swollen or bulged eyes. Protruding eyes are a characteristic of popeye in betta fish.

The scientific name of this condition is Exophthalmia, and popeye is not limited to bettas as it can affect almost all fish breeds.

Sometimes, the eyes may develop a ring or white splotches around them.

Popeye occurs due to the excessive buildup of pressure on the back side of the eyes that causes them to protrude out.

It’s not a lethal condition unless left untreated for a long time.

Types of betta fish popeye

Popeye has two types: Unilateral popeye and bilateral popeye.

It’s pretty self-explanatory; unilateral popeye is when popeye affects just one eye. On the other hand, bilateral popeye infects both eyes.

Causes of betta fish popeye

Almost anything that can cause excessive buildup of pressure on the backside of the eyes of betta fish could trigger popeye.

Experts believe that there’re two common causes of popeye: injury and infection.

Physical Injuries (traumas)

Injuries are the most common cause of unilateral popeye.

Any physical injury that affects the area around the eyes could cause a popeye.

For example, your betta fish may accidentally hit its eye on a decoration in the tank or have been fighting with a tank mate.

In that case, your betta fish can sustain a physical injury in the eye area, which could lead to popeye.


An infection could be the cause of bilateral popeye (both eyes) in your betta’s eyes are infected with popeye. The first thing you should look for is an infection.

There can be different types of infection, such as fungal infection, bacterial infection, or infection caused by parasites.

Any infection in the eye area of your betta fish could cause popeye in both eyes.

As there are several possible ways of pressure building behind your betta’s eyes, you can’t pinpoint a single particular reason or cause of popeye.

Signs and symptoms of betta fish popeye

As mentioned, swollen or protruding eyes are the most apparent symptom of popeye in betta fish. The bulging of one or both eyes is easily noticeable.

If you notice any swelling in your betta’s eye, it’s likely to be a sign of popeye. Therefore, you should immediately start treatment measures before becoming uncontrollable.

Some other common signs and symptoms that you may notice when your betta fish are suffering from popeye are as follows:

Colour changes in eyes

Besides swelling, you may also observe colour changes in the eyes of your bettas. If the eyes show cloudy or milky colour, it could indicate popeye.

It could also signify a ruptured cornea due to excessive pressure behind the eyes.

If the popeye has developed due to physical trauma or injury from a fight with a tank mate, you may notice the bloodshot appearance of the bettas’ eyes.

It usually happens due to the injury of the cornea.

White rings around the eyes

If you notice a white ring around one or both eyes of your betta fish, it could be an indication of popeye development.

In most cases, white rings appear as a symptom of popeye, which means you could notice rings around your betta’s eyes before the onset of popeye.

You should immediately start the treatment procedure after noticing white rings, even if the eye has no swelling.

Betta fish might feel lethargic

Your betta fish might feel lethargic when affected by popeye. They may feel tired, sleepy, and sluggish.

As a result, you won’t see your bettas move around the aquarium as much, and they will most likely hide behind decorations.

If your betta fish is suffering from popeye, you may notice a lower appetite than usual. They may avoid contact with other fish in the aquarium.

Under the effect of popeye, your betta fish may prefer to stay in the same spot for long periods without active movements.

In rare cases, betta fish with popeye may rest on the bottom of the aquarium for most of the day.

However, lethargy is a common symptom in a lot of diseases in betta fish, so make sure it pairs with the other symptoms above.

How to treat popeye in betta fish?

As mentioned earlier, there are two significant causes of popeye: physical injury and infection.

So, you may need to adopt a different treatment method depending on the cause of popeye.

Here, I will discuss the treatment methods for popeye in betta fish caused by both physical trauma and infections.

Treatment of popeye caused by physical injury or trauma

Suppose your betta fish have sustained popeye due to a physical injury or trauma resulting from a fight with a tank mate or bumping into a solid object within the aquarium.

In that case, you can use Epsom salt treatment to cure popeye.

Here are 4 steps you can use to effectively treat popeye with Epsom salt;

  1. Take a small container/aquarium with at least 8 to 15 litres (2 to 4 gallons) of water. Fill this container with the water from your betta’s aquarium.
  2. Add Epsom salt to the container per the manufacturer’s guidelines. You can find the right concentration that you can use to treat your bettas by checking the label of the Epsom salt pack. Dissolve the salt in the water by stirring.
  3. Once the salt has completely dissolved, make sure the temperature and water conditions are the same as your main aquariums.
  4. Place your bettas one by one in this container to give them a salt bath. You should keep your betta fish in the container for about 10 minutes to ensure they’re adequately bathed.

Instead of an Epsom salt bath, you can treat your betta fish with aquarium salt. Many other blogs recommend adding aquarium salt to your main aquarium for treatment and as a preventive.

However, I recommend against this. You might have other fish, shrimp, snails, and plants that might not tolerate the salinity.

And if you keep dosing aquarium salt directly, you will need to measure how much salt you’ve dosed over time constantly.

This is because you can’t totally remove salt once you add it to an aquarium without a complete overhaul.

And without proper measurements of how much you’ve added, you will increase the salinity to intolerable levels.

Instead, have a hospital tank or a container available to do this.

A salt bath – Epsom salt or aquarium salt – will help your betta fish recover from traumas or physical injuries and improve their immune system.

According to the International Betta Congress, aquarium salt is the best preventive and treatment solution for betta fish.

Treatment of popeye caused by infections (fungal, bacterial, or parasites)

If your betta fish is suffering from popeye due to any infection – such as bacterial infection, fungal infection, or infections caused by different parasites – the treatment method will be different from popeye caused by physical injuries.

Popeye caused by an infection is treated with a combination of aquarium salt and over-the-counter medications.

To treat a popeye infection in your betta fish, here are six steps to follow;

  1. Prepare a hospital tank. For this, I like to take a separate container with at least 35 litres (9 gallons) of water. I like to use larger volumes as it provides more room for error, especially when it comes to chemicals.
  2. As directed by the manufacturer, dose aquarium salt and antibacterial medications.
  3. Transfer your betta fish from the aquarium to the quarantine tank. Ensure it has the same temperature and water conditions as your main aquarium.
  4. Once you’ve transferred, the next step is changing the main aquarium’s water. The water changes should be 100%, which means you will take out the entire amount of water from the aquarium and replace it with fresh, clean water. This process is beneficial to make sure your aquarium has minimised the amount of infection-causing bacteria/viruses/fungi.
  5. Carry out the treatment according to the manufacturer’s instructions.
  6. I like to add Indian almond leaves to the main aquarium to prevent and treat infections. Read my guide on Indian almond leaves for bettas here.

How long does it take for betta fish to recover from popeye?

The effects, signs, and symptoms of popeye may last for many weeks to even months, so you shouldn’t be worried if your betta fish take longer to recover, or if they don’t show signs of improvement immediately.

You don’t need to panic about the protruding eyes as long as your bettas are eating normally and don’t show body colour changes (very evident in wild bettas).

However, carrying on with the aquarium salt treatment is a great way to speed up the recovery process of your betta fish.

It also helps boost the immune system of your bettas so they can deal with infections more effectively in the future.

Preventing popeye in betta fish

It is always good to take preventive measures to protect your betta fish from popeye.

But how can you prevent popeye?

Well, here are some ways I know:

How to prevent infections in betta fish

The most effective way to prevent infections in your betta fish is to keep the aquarium clean and maintain good water conditions.

For the ornamental betta splendens, most water conditions are fine as long as it’s stable, clean, and free from ammonia, nitrite, and nitrates.

However, wild bettas such as the betta macrostoma are more demanding of water conditions, so make sure you know how to keep them properly.

The first step to improving the water conditions is to have a proper filter for your bettas and regular maintenance of your filtration system.

Always remember that poor water conditions are an enemy to the immune system of your betta fish.

If the aquarium water is not clean and well-maintained, it could cause stress and weaken their immune system.

When betta fish have a weakened immune system, they’re vulnerable to diseases.

Following are some useful tips that will help prevent infections in your betta fish:

  • Avoid overcrowding of fish in your aquarium, as it could cause your filtration system to be inadequate. Too many fish in the aquarium can cause an excessive buildup of wastes – like ammonia, nitrites, and nitrates – that could quickly lead the filtration system to choke up. Territorial fishes like bettas are also unappreciative of constantly chasing fishes out of their territories.
  • Perform water changes regularly to keep the water conditions well-maintained and clean. You can carry out partial water changes weekly.
  • The frequency of water change depends on the size of your aquarium. Larger aquariums have room for less frequent water changes, but smaller tanks require it done frequently.
  • The next step is the regular maintenance of filters. The filter media is the most crucial part of the filtration system. The waste buildup could cause the filters to become clogged, reducing flow.
  • If you see any ill fish in the tank, quarantine them immediately before they infect others. You should always have a spare quarantine tank to keep sick fish.
  • Use Indian almond leaves for their antibacterial and antifungal properties.
  • Use plants to absorb the harmful ammonia, nitrite, and nitrates.

How to prevent physical injuries or traumas to your betta fish

Most preventive measures for physical injuries or traumas are similar to infections.

For example, avoiding overcrowding in the water tank can help prevent infections and physical harm.

However, some steps are specific to preventing physical injuries and traumas.

  • If you’ve any aggressive fish in the aquarium, immediately separate them from the peaceful ones. In most cases, fish behave aggressively when they’re made to live in overcrowded tanks. Some breeds are also aggressive, such as other betta fish, cichlids, and certain tetras that may fight with each other.
  • Don’t use plastic plants as decorations. Most plastic plants are sharp and can damage your betta fish.
  • Handle your betta fish carefully, especially when you’re using a net. Poor handling is a common cause of physical injuries in betta fish.
  • In large aquariums (90cm/3ft or larger), you may want to put more fish so that it’s more lively. If you do, make sure there are enough hiding spots across the tank for your bettas to retreat.


Although betta fish popeye is a condition that needs ongoing long-term treatment, it is easily preventable.

It’s rare to see betta fish die from popeye – unilateral or bilateral – unless they’re treated way too late.

So as always, observe your bettas for any form of disease so you can prevent and treat it early.

What I like to do as prevention is to decorate and set the water conditions according to their natural habitat, the species of betta, and regular water changes.

I also like to have smaller species-only tanks to prevent any fights.

This reduces stress and the chances of them getting affected by any illnesses.

I hope this guide has been helpful in treating and preventing popeye in betta fish, if you have any questions, please do leave them in the comments below!

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