How To Cure Popeye In Betta Fish – Causes, Treatment, & Prevention

    can betta fish die from popeye

    Diseases making their way into your aquarium can be quite stressful, even if you’re not a beginner in the fishkeeping hobby. Most betta fish owners will deal with Popeye Disease at least once, as their showoff pet fish is especially susceptible to it. Want to know how to cure Popeye in betta fish?

    Curing popeye in betta fish involves a series of steps that involve using salt baths, water changes, and antibiotics (if necessary). This guide will go over all of the details you need to know in order to successfully treat popeye in your betta.

    Stick around and you’ll find yourself much less intimidated by this disease by the end of this article!

    You might wonder how come you have to deal with Popeye disease in a clean and well-maintained betta tank.

    The truth is, this illness is rarely carried into the tank when buying new fish or when introducing new plants like other diseases are (such as white spot disease).

    It’s more often than not caused by an injury your betta fish has suffered, but it can be brought on by underlying issues as well.

    Let’s find out how to identify, treat and prevent Popeye disease in bettas!

    What Is Popeye Disease?

    unilateral popeye in betta

    Popeye disease, also known as exophthalmia, is an illness that creates pressure behind the eye of the fish, causing it to swell and eventually bulge out of its socket unnaturally.

    The term “unnaturally” fits appropriately because some fish species have naturally bulging eyes.

    Some breeds of fancy goldfish (i.e., Black Moor Goldfish and Celestial Eye Goldfish) have been bred to have “telescope eyes” ever since the 1700s in China to create the protruding eyes that resemble the eyes of a dragon.

    Popeye can affect most aquarium fish. If a betta, or more than one fish, living in a community tank develops bilateral Popeye disease, the cause will almost always be a bacterial or fungal infection.

    If the telltale signs of Popeye appear on only one side (unilateral Popeye disease), the most common culprit is an injury. There are plenty of ways bettas can get hurt in an aquarium.

    Popeyes disease will usually come with a number of other symptoms and signs, which makes it almost impossible to misdiagnose.

    Main Symptoms Of Popeye Disease In Betta Fish

    There are several notable symptoms of Popeye disease that you should definitely pay attention to.

    • Bulging eyes

    The easiest to identify symptoms associated with Popeye diseases in betta fish are the protruding eyes.

    This might happen in one eye (unilateral Popeye) or in both of them (bilateral Popeye).

    This is a sign that typically becomes noticeable once your betta has had the illness for some time, so treating it should be considered an emergency.

    • A white ring around the eye

    A white ring, or white splotches, inside the eye is a pretty reliable indicator that your pet betta fish might soon show other signs of Popeye disease. This is the symptom that often is the precursor of the full-blown illness setting in.

    If you’re lucky enough to notice this symptom ahead of time, start treating immediately to give your betta the best chances of getting cured of Popeye.

    Early treatment helps to ensure that there are no long-lasting negative effects (loss of vision in the affected eye is common if treated too late).  

    • Changes in eye color

    Changing eye colors in Popeye disease are usually associated with physical injuries and are more likely to occur in unilateral Popeye. 

    These color changes can range from a cloudy/milky appearance to red and bloodshot. Redness is more than likely caused by a ruptured cornea.

    Abnormal colored eyes and loss of vision will also affect bettas if Popeye is left untreated.

    Other symptoms to look out for:

    • Abnormal swimming, or no swimming at all;
    • Hiding from its tank mates instead of flaring to show dominance;
    • No interest in food during feedings;
    • Spending too much time in the lower level of the tank;
    • Not coming up for air as often.

    Healthy Betta Eyes

    Betta Eyes with Popeye Disease

    Flat Eyes popping out, on one or both sides
    Clear Opaque/cloudy/milky appearance
      Bloodshot color
      White ring eye contour


    If you notice these symptoms in your betta, it’s important to treat them as soon as possible.

    Here is a video that shows how you can treat popeye in your fish:

    What Causes Popeye Disease In Betta Fish?

    Many events can cause Popeye disease, so it can be difficult to pinpoint an exact cause of why it affects betta fish.

    The way in which Popeye manifests in your pet fish can give you some information about the event that might have brought it on.

    Factors like: a genetic predisposition to the illness, an underlying water quality issue, a bacterial/fungal infection spreading inside your tank, etc., will usually result in a bilateral Popeye infection, affecting both of your betta’s eyes.

    If your betta is the only one to suffer from Popeye in a community tank, or if just one eye displays obvious signs of the diseases, it’s a good indicator that your betta fish has a unilateral Popeye infection.

    Sometimes, a combination of factors can create the “perfect storm” for a Popeye infection. Bettas suffering a physical injury at eye level can have a harder time surviving the illness if the water chemistry inside their tank is off, making them more susceptible to diseases in general.

    There are Popeye infections in bettas that can get resolved by the fish’s immune system alone, but with so many factors that can overturn this “best-case scenario”, it’s best that you monitor and treat your pet betta fish to make sure it survives.

    So, how do you cure Popeye in betta fish? And how do you prevent recurrent infections?

    Unilateral Popeye | Causes, Treatment & Prevention

    A unilateral Popeye infection will only affect one of your betta fish’s eyes. 


    Unilateral Popeye infections are triggered by physical trauma most times.

    Whether your betta gets injured by scraping its eye against a sharp-edged decoration, or it gets hurt during a fight with one of its tankmates, the damage will leave it vulnerable to developing Popeye.


    When bettas develop unilateral Popeye disease due to an injury, they are easier to treat and cure. That’s because there isn’t an underlying issue that’s facilitating a recurring Popeye infection.

    In this case, some bettas are lucky enough to have the protruding eye recede back to its normal state on its own. However, treating your betta for Popeye disease is the best course of action:

    Here’s how to cure unilateral Popeye in betta fish:

    • Add tank water (from your betta’s aquarium) in a clean container.
    • Add aquarium salt (the kind aquarists would use in a saltwater tank), or Epsom salt, into the container. It’s useful to know the volume of water you have inside the container, as you’ll need to add one tablespoon of aquarium/Epsom salt per gallon of water.
    • Move your Popeye infected betta fish into the container once the salt is dissolved, and leave it there between 10 to 15 minutes.
    • This “salt bath” is meant to reduce inflammation, swelling and alleviate the infection.
    • To make sure the water inside the clean container remains at an acceptable temperature, you can float it inside the betta’s tank, like you would when acclimating a new fish.
    • You can use this treatment a few times per week until the protruding eye goes back to its normal position.
    • “Salt baths” aren’t harmful to bettas. Some fishkeepers actually add aquarium salt inside their betta tank as a way to keep their immune system in tiptop shape. Avoid doing this if your betta’s tank mates are sensitive to any changes in salinity levels.


    To avoid future injuries, which are the usual culprits in unilateral Popeye infections in betta fish, consider taking some (or all) of these preventive steps:

    • Separate your betta from incompatible tank mates

    Betta fish are considered aggressive aquarium fish, mostly because they are territorial and will fight other fish, especially other male bettas, that trespass into their territory.

    If you keep two male betta fish in the same tank, you’re just asking for trouble!

    Your betta can also become the victim of bullying if you’re having them share a tank with notorious fin nippers. Their long-flowing fins make them preferred targets for Angelfish, some barbs, and some tetras.

    If any of these situations sound familiar, it’s time you move your betta into another tank to avoid even more injuries and recurrent Popeye infections.

    • Get rid of fake plants

    Fake plants inside a betta tank can be a low-maintenance alternative to live aquatic plants, but they’re actually a dangerous obstacle for your betta.

    Their long sensitive fins can get snagged up by the tips of plastic plants. These fake plants are sharp enough to scrape against a betta’s eyes, causing substantial physical trauma.

    Any area of your betta fish’s body that gets damaged by fake plants can become vulnerable to a number of bacterial infections, not just Popeye disease.

    Choose silky live plants instead, as bettas love to rest and hide among plants.

    • Transfer using cups instead of fish nets

    Catching, moving, and releasing betta fish during transfers can be nerve-wracking, mostly because their paper-thin fins can easily tear. A transfer-related injury to a betta’s eye can cause a unilateral Popeye infection.

    To avoid these injuries, use a clean cup, rather than maneuvering a fish net when handling a betta fish.

    They tend to come to the water surface often enough to make it easy for you to catch them using a cup.

    • Avoid sudden changes in a betta’s environment

    When startled, betta fish can dart across their tank, bumping into anything that happens to be in their way.

    They can get startled because of things that you won’t consider to be as “sudden” as they look like for a betta: turning the aquarium light on in pitch darkness or something dropping against their tank.

    Even sudden movements outside the glass panels can trigger your betta to dash into plants, decorations, or the tank’s walls. So, try to avoid startling your betta to prevent it from inadvertedly injuring itself.

    • Get a filter with an adjustable flow

    Bettas aren’t naturally equipped for swimming in strong currents. That’s why a tank filter with too strong of a flow can put your betta at risk for injuries.

    Especially if your betta fish is in a nano tank, by itself you won’t need a filter strong enough to cause it harm. But just to be safe, opt for a filtering system that has an adjustable flow.

    If your betta is in a community tank and you’ve had them get injured because they got pushed by the filter’s current, you can try changing your filter’s position.

    Having the flow dissipated by an obstacle (décor/plant) is enough to prevent your betta from getting thrown about in the tank.

    Bilateral Popeye | Causes Treatment & Prevention

    Bilateral Popeye infections in betta fish will affect both eyes.


    Bilateral Popeye is usually triggered by an underlying condition that might be spreading under the radar inside your betta’s tank.

    Conditions like bacterial infections, fungal infections, or parasitic infestations, as well as stress factors that leave your betta vulnerable to diseases, can all cause bilateral Popeye infections.


    Whether or not you can narrow down the underlying issues that your betta fish is dealing with, along with a bilateral Popeye infection, the course of action follows a particular pattern.

    Here’s how to cure bilateral Popeye in betta fish:

    • Quarantine your betta fish in a “hospital” aquarium, removing it from a community tank as soon as possible. Popeye doesn’t necessarily spread, but the underlying condition might.
    • Do a major water change inside the tank that you’ve just removed your betta from.
      A 70% water change on the first day, followed by a week of smaller daily water changes, should protect the betta’s tank mates from contracting the same disease.
    • If your betta fish isn’t the only one affected, move other Popeye infected fish into the same quarantine tank as your betta.
    • Add aquarium salt/Epsom salt to the quarantine tank, following the one tablespoon per gallon of water rule of thumb. This will help with the swelling and inflammation while dosing medicine.
    • Dose the quarantine tank with over-the-counter broad-spectrum antibiotics (a veterinarian/pet shop will help with exact medication recommendations and appropriate dosages).
    • Perform 100% water changes daily (for at least three days) inside the quarantine tank, adding salt/antibiotics as advised.
    • Monitor your betta (and other infected fish) for ten days, keeping them in the quarantine tank.
    • If the underlying condition that triggered the bilateral Popeye infection turns out to be a parasitic infestation, you might need to dose a vet-recommended treatment inside the betta’s community tank as well.


    To protect your betta from developing bilateral Popeye disease, you’ll need to take measures that will keep stress levels low immune system to work efficiently:

    • Work on your betta tank’s water quality

    Water quality is the ultimate external factor that influences an aquarium fish’s immune response to diseases, bacteria, or fungus. And that’s because lower than standard water quality puts stress on your betta’s immunity, leaving it vulnerable to not only Popeye, but a cohort of other conditions.

    Here are the optimal water parameters for a betta fish tank:

    pH 6.8-7.5
    Water hardness 3-5 dKH
    Temperature 76-85°F
    Ammonia/nitrites 0 ppm
    Nitrates <20 ppm


    You can use freshwater test kits to monitor and make sure these water parameters stay within acceptable ranges.

    • Carry out 20% water changes weekly

    Water changes are essential in a betta fish tank, especially if you’re keeping your betta in a nano tank (<20 gallons) and if you have an unfiltered aquarium setup.

    Doing 20% water changes weekly will keep the nitrate levels inside your betta’s tank within a safe range, preventing the water inside the tank from becoming toxic for your brightly colored splendor.

    Neglecting this aquarium maintenance step will put your betta at risk for developing bilateral Popeye. 

    • Avoid overcrowding

    Overstocking a community tank or just adding too many fish/critters in a betta’s tank can create a biological overload. This happens when excessive fish waste turns into ammonia quicker than the good bacteria inside the tank can convert ammonia into non-toxic nitrates.

    Water quality can plummet if you overcrowd a fish tank! And as water quality drops, the risk for disease skyrockets.

    • Clean/change filter media as needed

    Filter media is an excellent breeding ground for the good bacteria inside your betta fish tank, but you should be cleaning/replacing it regularly.

    Filter sponges can get covered in debris, leftover fish food, and other waste products, preventing your tank’s filtering system from working at peak efficiency. Chemical filter media (activated carbon) can lose its efficiency after 3-6 months of use.

    Stay on top of a regular filter cleaning routine to keep your betta disease-free!

    • Quarantine/clean new additions

    Bilateral Popeye disease isn’t typically contagious, but the underlying infections that trigger it can make their way into your betta’s tank when introducing new fish. That’s why you should quarantine new fish for at least two weeks, before adding them into a community tank.

    Similarly, live plants can carry hitchhiking parasites, so they should be cleaned thoroughly using old tank water before you plant them inside your betta’s aquarium.

    • Remove and quarantine sick fish

    Whenever your pet fish start to show obvious signs of disease (lethargy, lack of appetite, not moving from one spot), move them in a quarantine tank as soon as possible. The quicker you isolate a sick fish, the more chances you have of having fewer infected fish.


    betta popeye epsom salt

    How long does it take for betta fish to get cured of Popeye Disease?

    It can take up to a few weeks, sometimes a month, for the protruding eyes in a Popeye infected betta to go back to normal.

    If your betta fish regains its appetite and resumes to its normal activity level, you don’t have to worry about the bulging eyes, as they will go back to their normal shape eventually.

    Can you speed up a betta’s recovery from Popeye Disease?

    You should follow a strict tank cleaning routine (no slacking!) while your betta is recovering from a Popeye infection to make sure it isn’t facing even more stress than it’s already dealing with.

    Some fishkeepers switch to higher quality fish food for a while to boost their betta’s immune system.

    How contagious is Popeye Disease?

    Popeye infections are not contagious themselves; it’s the underlying conditions that trigger this disease that can be contagious. That’s why quarantining a betta suffering from Popeye is highly recommended.

    Can betta fish die from Popeye Disease?

    If left untreated or treated too late, Popeye can, unfortunately, be fatal to a betta fish that’s living in poor water conditions or just has a weaker immune system in general.

    Most Popeye-related fish deaths happen if the eye ruptures from the swelling, that’s why inflammation-alleviating “salt baths” are crucial in both unilateral and bilateral Popeye infections.

    Conclusion – How To Cure Popeye In Betta Fish

    You can 100% cure your betta of Popeye disease. Make sure you monitor your splendor regularly and start treating it as quickly as possible if you spot the distinctive signs of a Popeye infection.

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