betta fish popeye

Betta Fish Popeye: Symptoms, Treatment, and Prevention

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If your betta fish develops Popeye, it can be quite alarming. However, the condition is easy to diagnose and, with the right care and treatment, Popeye is curable.

Read this guide to find out what causes Popeye in betta fish and learn how to diagnose, treat, and prevent the condition.

What Is Popeye?

It’s not just bettas that can be affected by Popeye. The condition can affect any fish species, animals, and people, too!

The proper name for Popeye is exophthalmia, and the condition occurs when a build-up of pressure behind the eye causes it to protrude. Popeye is actually easier to prevent than it is to treat, and if you don’t treat the problem quickly, your betta buddy could die.

What Causes Popeye?

There are several causes of Popeye, and it can be difficult to pinpoint one reason for the condition, making effectively treating the problem somewhat tricky. Popeye can affect one or both eyes.

Unilateral Popeye

Unilateral Popeye affects just one eye. In most cases, unilateral Popeye is caused by a trauma of some kind, resulting in physical injury.

For example, your fish may bump into something in his tank or have a scrap with a tankmate.

Bilateral Popeye

Popeye affecting both eyes is called bilateral Popeye. In these cases, the cause is usually some kind of infection.

That can be caused by parasite activity, bacteria, or fungus, and is often accompanied by more general symptoms, affecting the whole fish.

Betta Fish Popeye: Symptoms and Signs

There are several signs and symptoms of Popeye in betta fish. Let’s examine these in further detail:

Protruding eyes

The most obvious sign of Popeye is that the fish’s eyes protrude or bulge. As previously mentioned, the condition can affect one or both eyes.

Eyes changing color

betta fish with popeye in fish bowl

In some cases, the fish’s eye or eyes may change color, as well as protrude. If the eye appears cloudy or milky, it could be that the cornea has ruptured.

The eyes may appear bloodshot, which generally results from some act of physical trauma, commonly fighting with another fish.

White-ringed eyes

A white ring around your betta’s eye is generally an indication that he will develop Popeye. If you notice this symptom, you need to start treating your fish for Popeye right away.

Other symptoms of sickness

Other common signs of sickness to watch out for in your pet include the following:

  • lethargy
  • loss of appetite
  • avoiding other fish
  • remaining in the same spot for long periods
  • resting on the bottom of the tank

Treating Popeye

How you can treat Popeye in betta fish depends on the cause, so let’s take a look at the reasons why your fish has developed this condition, and what you can do about it:

 Physical trauma

If your betta’s Popeye has been caused by physical trauma, it’s less likely to be fatal than if a disease causes the condition.

To treat Popeye that’s been caused by an injury after a fight or by your pet bumping into something in his tank, follow these instructions:


  • Remove some water from your betta’s tank and use it to fill a container.
  • Fill the container with Epsom salt, following the manufacturer’s guidelines. Once the salt has dissolved, place your betta into the Epsom salt bath.
  • Leave your pet in the bath for at least ten minutes.
  • During your betta’s bath, float the container in his tank so that the water stays at the correct temperature.

Alternatively, you can add aquarium salt to your betta’s tank, which will help boost your pet’s immune system and aid in a speedy recovery from his injuries.

In fact, the International Betta Congress recommends that you add aquarium salt to your betta’s tank as a general tonic.

Disease or parasites

If Popeye is caused by a bacterial infection or the action of parasites, the treatment is different. Follow the instructions below to treat the problem:


  • First of all, set up a quarantine tank and move your betta into it.
  • Once your betta is safely installed in the hospital tank, you should carry out a 100% water change on your main tank to eliminate whatever is causing the infection and protect your remaining fish.
  • Treat your betta with aquarium salt and over-the-counter antibacterial medication that you’ll get from a good fish store.
  • Change all the water in the quarantine tank every three days, and add fresh aquarium salt and medication.
  • After 10 days, stop treating the water with medication. Your betta should be showing signs of improvement by now.

Recovery time from Popeye

Popeye can take many weeks or even months to clear up completely, so don’t panic if your betta doesn’t recover immediately.

As long as your pet eats and appears back to his usual self, the bulging eye will gradually resolve itself.

It’s a good idea to continue treating the tank with aquarium salt as a general pick-me-up during your pet’s recovery.

How to Prevent Popeye in Betta Fish

It’s always better to prevent a problem than to try to cure it. So, how can you prevent your betta fish from developing Popeye?

Preventing Infection

The best way to prevent infection is to keep the water conditions in your fish tank clean and your filtration system properly maintained.

Poor water quality causes stress, and a stressed betta will have a weakened immune system that leaves him open to attack by diseases and parasites.


If you have too many fish in your tank, the filter system will struggle to remove ammonia, nitrites, and nitrates from the water quickly enough to keep the environment healthy.

Once the levels of those harmful chemicals rise, your fish will begin to suffer and are at risk of infection and disease.

Water changes

You should carry out partial water changes every week, depending on the size of your setup and the number of fish you have.

Generally, the larger your tank, the less frequent the water changes need to be, unless you have a lot of fish.

Maintain the filters

The filter media in your filter system can quickly become clogged with sludge, which means that the water flow won’t be as good.

For the biological filter to work properly, the tank water needs to flow across the filter media so that the bacteria that live there can consume and process the waste products in the water.

Every month or so, you need to remove the filter media and rinse it through in tank water. Generally, every three months or so, the filter media will probably need replacement, depending on the manufacturer’s recommendations.

Quarantine sick fish

If you spot any fish in the tank that are showing signs of disease, remove them right away to a quarantine tank where they can be treated.

How To Prevent Physical Trauma to Betta Fish

Physical trauma is probably the most common cause of Popeye in betta fish, but there are steps that you can take to keep your pet protected.

Remove aggressive tankmates

Although betta fish are generally peaceful when kept with amenable tankmates of another species, they aren’t called Siamese Fighting fish for no reason, and there are always exceptions.

If you have a very aggressive betta or there are other fish that cause trouble in the tank and just don’t get along with your betta, you’ll need to remove and relocate one of the warring parties.

You may be able to give an unwanted fish to your local fish store or perhaps pass it on to a friend. However, if neither of those options is viable, you may need to buy a separate, small tank for your betta so that he can live in solitary, peaceful splendor.

Plastic plants

Plastic plants can be very sharp and potentially damaging to your betta. For that reason, we recommend that you use living or silk plants instead of plastic ones.

Sharp plastic can easily snag on your betta’s fins or poke its eye, leading to Popeye and potentially allowing bacteria to enter the fish’s body and cause an infection.

Handle with care

If you need to handle your betta buddy, do that very gently and carefully, especially when using a net.

Many fish are injured through poor handling by their owners, even accidentally. Take your time, and be sure to lift your fish gently and slowly.

Light ’em up!

In nature, the sun rises slowly, gradually filling the environment with light. However, in the home, when you turn on your fish tank light in the morning, the whole aquarium is flooded with bright light right away.

That can be traumatic and stressful for your betta, and he may dart frantically around the tank, bumping into things and potentially injuring himself.

There are two things that you can do to solve this problem. First of all, try switching on your room lights and waiting for ten minutes or so before turning on your tank lights. That will give your betta a chance to acclimatize before his habitat is flooded with light.

Secondly, you could upgrade your aquarium lighting unit to one that has an automatic timer that features a sunrise and moonlight setting.

These lighting units gradually phase in the lights to replicate the natural sunrise and are perfect for a skittish betta.

Going with the flow

In nature, betta fish live in bodies of water that have little or no current. Your betta tank will have a filtration system in the captive environment, and sometimes the mechanical filter element can generate a very strong flow.

That’s great for keeping your tank clean and removing harmful chemicals from the water, but it can spell trouble for a betta fish.

Bettas aren’t the most agile of swimmers, and they can easily be buffeted around by a powerful current in the tank. That may cause your fish to collide with the decorations in the tank, potentially sustaining an injury in the process.

You can help to prevent that from happening by angling the flow from your pump so that plants or pieces of tank decor buffer it. You can also buy small plastic buffer attachments that you can fit onto the filter outflow valve.

Will Popeye Heal on Its Own?

Yes, if the underlying cause is due to a physical injury, the Popeye should heal on its own in time. However, if Popeye is caused by an infection, it’s important to consult a veterinarian to get the appropriate antibiotics to treat the infection. Otherwise, it is possible for the infection to cause further damage.

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