How To Cure Popeye In Betta Fish – Treatment & Prevention

I know that awful feeling of seeing your fish's eyes bulging and wondering what’s going on, what you've done wrong, and more importantly, what can you do about it. Having successfully dealt with popeye myself, I can tell you it’s actually pretty easy to identify and treat with the right care.
How to cure popeye in betta fish

With that in mind, I’ve put together this how to cure popeye in betta fish guide so you can get your betta back to its best as quickly as possible.

What Is Popeye Disease?

Known medically as exophthalmia, popeye can affect any fish, not just betta fish.

Pressure builds behind the fish’s eyes, causing them to protrude or appear swollen.

Both eyes (bilateral) or just one eye (unilateral) can be affected.

This article will discuss the symptoms, treatment, and prevention of popeye in betta fish.

Normal Betta Eyes vs Popeye

Your betta’s eyes should be evenly sized, clear, and not protruding too much (left image), in the image on the right you can clearly see the betta fish eye is swollen and has a cloudy appearance.

If your betta has one or two swollen eyes, you must treat it for popeye immediately, I’ve recommended some treatment plans below.

normal betta eyes vs popeye
(left) Normal betta eyes vs popeye (right)

Symptoms Of Popeye In Betta Fish

The symptoms of your betta having popeye are:

Protruding, Bulging, or Swollen Eyes

This is the most obvious sign that your betta fish has popeye, one or both eyes can be affected.

If you notice that your betta’s eyes are bulging, you should treat it for popeye as soon as possible.

White Ring Around Eyes

If you notice a white ring or splotches around your betta fish’s eye or eyes, this can be an early warning sign before your betta gets full-blown popeye.

You should treat your betta for popeye straight away.

Eyes Change Color

Your fish’s eye may appear cloudy or milky if the cornea has been damaged.

Physical trauma or injury may cause your fish’s eye to appear bloodshot.

Other Symptoms That Your Betta Fish Is Unwell Are:

  • Appearing lethargic
  • Bruising or scale loss – this will be a sign that your fish has been flashing
  • Clamped fins
  • Flashing – flattening themselves out at the bottom of the tank and rubbing against the substrate or decor, twitchy swimming, sudden bursts of swimming, or even jumping out of the water
  • Hiding more than normal
  • Loss of appetite
  • Pale coloration

What Causes Popeye In Betta Fish?

There is no single cause of popeye, as there are 2 types of this condition.

  1. Unilateral popeye (one bulging eye)
  2. Bilateral popeye (two bulging eyes)

Both of these have different causes and you have to know which one your betta has in order to provide the correct treatment.

To keep things simple, I’ll go over each of the above in separate sections, starting with unilateral popeye.

1. Causes of Unilateral Popeye (One Bulging Eye)

Physical trauma is generally the cause of unilateral popeye.

This can be caused by an aggressive tank mate or sharp objects in your betta’s tank.

Treatment For Physical Trauma

Unilateral popeye is generally easier to treat and cure than bilateral popeye as it’s not caused by an underlying health condition or infection.

Treat your betta fish with aquarium salt.

API Aquarium Salt

Do not use regular iodized table salt or marine salt in a freshwater aquarium.
Table salt contains additives that are harmful to fish.
Marine salt is a completely different type of salt.

If your betta lives alone, you can add salt straight into the tank water.

If your betta fish has tank mates, it’s best to isolate it in a quarantine tank.

Dose the tank or quarantine tank as follows:

  • 1 tablespoon of aquarium salt per 3 gallons (11.4 liters) of water.

This low dosage is fine for most salt-sensitive species like cory catfish, but always do your research on the species of fish that you have.

I dissolve the salt in a small cup of water before adding it to my tank, that way I don’t risk irritating my fish if they come into contact with any undissolved grains of salt.

Leave the salt in the tank water until the fish starts to show improvement.

You can then start to remove the salt by performing 25-30% water changes each week.

Prevention Of Physical Trauma

Preventing unilateral popeye in betta fish is pretty easy, once you’ve figured out what’s causing it.

Remove Aggressive Tank Mates

There is a reason betta fish are also known as Siamese fighting fish! It is advisable to keep them alone.

You should watch out for aggressive tank mates if you keep betta fish in a community tank.

Fin nipping or aggressive behavior towards your betta can result in fights and injury.

Angelfish, barbs, and some tetras are known to be fin nippers.

Remove Plastic Plants

Remove plastic plants

Plastic plants have sharp edges that can tear your betta’s fins or poke them in the eye, causing injury.

Real or silk plants are a much better alternative.

Betta fish like to hide amongst or rest on plants, some great live plant options for betta fish are:

  • Anubias nana
  • Duckweed
  • Java fern
  • Water sprite

Remove Decor Items With Sharp Edges

Decor items like rocks, driftwood, or that really cool Star Wars ornament that you love, can have sharp edges on them that can damage your betta’s eyes should it bump into them.

Either file down the sharp edges or remove these items from the tank altogether.

Check Filter Flow Rate

Betta fish have beautiful long flowing fins, but this means they are slow swimmers and not designed to swim in strong currents.

If the water flow from your filter is too strong, a betta fish can end up getting bashed into objects in the tank, resulting in injury.

Reduce the flow of your filter if possible, or buy a filter with an adjustable flow rate.

2. Causes Of Bilateral Popeye (Two Bulging Eyes)

An underlying condition generally causes bilateral popeye, it can be tricky to figure out what’s causing the problem, so we’ll cover the most common causes.

The first step should always be to check and test the tank water. It may seem clean, but the levels of toxicity may be high.

If the water quality is good, there may be some other form of stress factor within your betta’s tank, such as bacterial, fungal, or parasitic infection.

It could also be an issue with your betta’s kidneys or gills, causing water to build up in the tissue behind the eyes, so they start to bulge or protrude.

If that’s the case, this is a serious problem and you should seek veterinary advice as soon as possible as your fish may have dropsy!

Treatment For Bilateral Popeye

If your betta is in a community tank, remove it straight away and place it in a quarantine/hospital tank for treatment.

As bilateral popeye could be caused by a bacterial infection, it’s best practice to treat the entire display tank too.

Perform a 75% water change on the tank you have just removed your betta fish from, and then perform 25% water changes each following day for a week. 

This will remove any infection in the water and help prevent your other fish from getting infected.

Monitor the community tank for any signs of popeye in your other fish.

Disclaimer: I’m not a qualified veterinarian, just a guy who loves keeping fish.

This is the method I have successfully used as a popeye betta treatment plan in the past.

Treat your betta fish with aquarium salt and medicine for bacterial infections. I’ve treated bilateral popeye successfully with Seachem KanaPlex.

API Aquarium Salt
API Aquarium Salt
Seachem KanaPlex
  1. Add 1 tablespoon of aquarium salt per gallon of water to the quarantine tank, this will help with inflammation and swelling.
  2. Dose the quarantine tank with KanaPlex, carefully following the dosage instructions.
  3. Perform a full water change to the quarantine tank every 48 hours and re-dose with the aquarium salt and KanaPlex medication.
  4. If you don’t see any improvement after the full course of treatment, contact a vet, as your betta may need stronger medication or may have a more serious underlying issue.

I have left a link at the bottom of this post where you can find a specialist fish vet in your area.

Prevention Of Bilateral Popeye

There are several things you can do to prevent your betta from getting bilateral popeye.

Water Quality

Most Accurate Kit
$50.48 $32.39

The API freshwater test kit offers outstanding value (over 800 tests!) and is very accurate, if you're serious about fishkeeping this is the best test kit to buy and the only one I use.

  • Includes 7 bottles of testing solutions, 1 color card, and 4 tubes with caps.
  • Performs over 800 tests.
  • Accurately monitors the 5 most vital water parameter levels in freshwater aquariums: pH, high range pH, ammonia, nitrite, and nitrate.
  • Helps monitor water quality and prevent invisible water problems that can be harmful to fish and cause fish loss.
  • More time consuming than test strips
Buy On Amazon Buy On Chewy
As an Amazon associate, I earn from qualifying purchases. This is at no additional cost to yourself.
04/12/2024 09:17 am GMT

Not maintaining a clean tank is the no.1 reason why fish become ill.

Poor water quality causes stress and weakens their immune system, leaving them open to diseases and infections.

If your betta (or any other type of fish) is showing any signs of illness, the first thing you should do is test whether the water parameters are optimum for your fish.

Quarantine New Tank Mates

Many people skip this, as it seems like too much hassle.

If you don’t quarantine new tank mates, you can very easily end up with a tank full of infected fish that you need to treat.

Ich in particular can be a nightmare to get rid of!

Quarantine new fish for 4-6 weeks, this gives you time to spot and treat any disease they may be carrying, before adding them to your main tank.

Avoid Overstocking Your Tank

Overstocking your tank increases the amount of waste (poop, rotting food etc) in your tank, putting strain on the nitrogen cycle.

If there is too much waste in your tank, the nitrifying bacteria will not be able to keep the ammonia, nitrites, and nitrates at safe levels for your fish.

This will stress your fish, weaken their immune system, and leave them more open to disease and infections.

You’ll need to upgrade to a larger tank or re-home some of the fish to solve this.

Clean Your Filter

Filters are a great breeding ground for beneficial bacteria, but they eventually get clogged up with sludge and debris.

Every month or so, in a separate container or large ziplock bag, rinse your filter media in tank water.

Do not use tap water to clean your filter media.
Tap water contains chlorine or chloramine that will kill the beneficial bacteria you’ve colonized.

Use the dirty filter water to water your plants, they’ll love it…you can’t buy better fertilizer than this!

If the filter media is beyond rinsing and needs replacing, do this gradually and replace around 30% of the filter media at a time, over the course of several weeks.

This is so that the beneficial bacteria have time to colonize the new filter media.

How To Cure Popeye In Betta Fish FAQ

Some frequently asked questions are:

Can Betta Fish Recover From Popeye?

Yes, a betta fish can usually recover from popeye, if it is treated quickly enough.

If your betta fish doesn’t respond to the treatments recommended above, take it to a vet as it may have a more serious underlying issue, such as a tumor.

What Antibiotic Treats Popeye In Fish?

Look for a medicine that treats bacterial and fungal infections.

I’ve successfully used KanaPlex by Seachem for treating popeye in betta fish.

Use this product simultaneously with aquarium salt for the best chance of recovery.

Does Melaxfix Help Popeye?

Yes, API Melafix can help treat popeye, although I’ve found KanaPlex to be more effective.

Can Aquarium Salt Or Epsom Salt Fix Popeye In Betta Fish?

Yes, both of these can be effective in treating fish popeye following the treatment instructions above.

When using Epsom salts, make sure they are pure and unscented.

Aquarium salt can be added to your betta’s tank, even when it is not ill as it can offer many benefits.

Can Betta Die From Popeye?

Fish don’t die from popeye itself, as it is caused by an underlying issue or trauma to the eye.

Sometimes a betta fish will lose an eye if it is badly damaged, but it can survive fine with only one eye.

If betta popeye is caused by an underlying issue, such as dirty tank water, disease, or infection, it can die from that if not treated.

Is Popeye Contagious?

Popeye itself isn’t contagious, but the underlying issue that has caused it may be contagious.

If your betta has one swollen eye, chances are it’s caused by trauma, therefore it’s not contagious.

If your betta has two swollen eyes, it is probably caused by disease or infection, which could be contagious.

Find a Fish Vet Near Me

If you would like to seek veterinary advice you can find a specialist aquatic vet in your area using the links below:

Closing Thoughts On How To Cure Popeye In Betta Fish?…

Now you know how to spot, treat and prevent popeye in a betta fish, or any other fish.

Bettas are great fish for beginners and advanced fishkeepers alike, you can’t fail to be dazzled by their colorful flowing fins.

Read my betta fish care guide for all the information you need for a happy and healthy betta fish.

The aquarium health section has more in-depth guides like this for keeping your fish tank in tip-top shape.



Hey, fellow fish enthusiast 👋! I'm Paul and I've been an aquarium addict since I won my first goldfish at the fair many years ago. Let me share with you the knowledge that I've gained along the way (and avoid the mistakes I've made!), so you too can create an underwater paradise for your aquatic friends.