Popeye in Goldfish (Causes, Symptoms, Treatment, & Prevention)

Last Updated on 2023-12-19

If you take good care of your aquarium, you’ll soon notice it if your goldfish is suffering from popeye. Popeye in goldfish is actually a generic term that can refer to several underlying problems.  

Read on to learn about what causes popeye in goldfish and how to best handle the problem. 

What is Popeye Disease in Goldfish? 

Popeye disease is medically known as exophthalmia. It is a condition where the eye of your goldfish becomes swollen and protrudes abnormally from its socket. Popeye disease may affect only one eye or both.  

In some cases, the eye will not show any other symptoms apart from the obvious swelling. Sometimes, though, it can appear cloudy or discolored and even bloodstained. If left untreated, the affected eye may eventually rupture, causing your goldfish to go blind.  

What Causes Popeye in Goldfish? 

Popeye, being more of a symptom than an actual disease, is a clear signal that something is not right with your goldfish or its environment. The popeye itself is caused by fluid leaking into the area behind your fish’s eyeball. If left untreated, the eye may even rupture or fall out of its socket. 

There is a variety of possible underlying causes, and in some cases, the real cause may never be determined. Don’t worry; we’ll look at what you can do to deal with popeye, no matter the cause, a little later on. 

Physical Injury 

Take the time to observe not only the goldfish you suspect to be affected by popeye but also the other fish in your tank if you have more than one. 

Sometimes, only one of the eyes on your goldfish will be affected. It may also be the case that if you have multiple goldfish in your aquarium, only one is suffering from popeye. And lookout for any visible signs of external damage to the eye. 

If what you see resonates with what we’ve just talked about, chances are your goldfish is suffering from popeye as a result of direct physical injury rather than a disease or infection. 

Physical injury can be the result of your goldfish scraping itself on some abrasive object in your tank as it is swimming. It can also happen when male goldfish get territorial and fight with each other over tank space and females. 

If your goldfishes are housed with other, more aggressive fish, they may also end up damaging their eyes on tank objects as they try to escape their aggressors. 

Parasitic Infections 

Another potential cause of popeye in goldfish is a parasitic infection. Popeye resulting from a parasitic infection will often affect both eyes in a fish, rather than just the one.  

It may be hard to notice at first, but popeye, due to parasitic infections, will gradually get worse. If you have multiple fish in your tank, only one may be affected at first. However, other fish will also likely get infected over time since they share the same water. 

Bacterial Infections 

Bacterial infections can also be the root cause behind popeye in your goldfish. Like parasitic infections, an affected goldfish is more likely to have both eyes sick than just one.  

Bacterial infections can also affect other fish sharing the same tank with time. So if you see other fish developing popeye too, bacteria are a prime suspect. 

If your goldfish starts having black spots, however, here are the reasons why!

Internal Problems 

Sometimes, popeye in goldfish can be the result of internal problems that have nothing to do with bacteria or parasites. Goldfish can and do suffer from various diseases, and popeye can be one of the external systems of such a condition. 

Unfortunately, diagnosing the underlying disease, if it’s an internal one, can be really hard, even for qualified veterinarians. There is a range of conditions that could cause popeye in goldfish, from kidney failure and metabolic issues to tuberculosis. 

If the cause of popeye is an internal problem, the chances are that your fish has already been in poor health for some time. In cases like these, popeye is frequently one of the later symptoms to show through. 

Dirty Water 

It is very, very important to keep your fish tank clean. You don’t need to do a thorough cleaning every single day, but you still need to be regular about it.  

If you don’t clean your tank frequently enough, the water becomes denser. It gradually decreases in quality, becoming rich in food waste and ammonia. Dirty water becomes the perfect breeding ground for bacteria and parasites. 

When goldfish are forced to live in dirty water, their immunity will gradually weaken, and they’ll end up falling prey to the parasites and bacteria inhabiting their tank. The most fragile fish will be affected first. Eventually, you could end up with all the fish in your tank, falling sick. 

(If the water stays dirty, then the chances of your goldfish suffering from ammonia poisoning, this is also one of the reasons your goldfish needs a filter.)

What Are The Symptoms of Popeye? 

Popeye may creep in gradually, making it hard to spot right away. But if you pay regular attention to your tank and spend time observing your fish, chances are you’ll notice something is wrong sooner rather than later. 

Even if you are a novice at keeping fish, popeye is relatively easy to identify. The harder part can be figuring out what is causing the popeye. So if you’re reasonably sure it’s popeye but can’t work out what the problem could be, you might need to seek help from a more experienced fish keeper or pay your vet a visit. 

Slight Bulging on One or Both Eyes 

When popeye first appears, especially if it is not due to a physical injury, it may not become prominent for a few days. It may be quite hard to notice, and when you first see it at this stage, you may doubt yourself. 

At this point, you need to be on the lookout for a very slight protrusion of one or both eyes. There likely won’t be any other visible symptoms, like a change of eye color or your fish swimming sluggishly.  

As we said, this slight bulging may not at all be obvious, especially if you’re a novice or if you haven’t spent much time around your tank of late and haven’t critically been observing your fish the past few days.  

One or Both Eyes Severely Protruding 

When it gets to this stage, it becomes glaringly obvious, even if you don’t have any experience with popeye and don’t feel confident in what to look for. The affected eye looks like it’s literally about to pop out of the socket completely. 

You may also be able to see the bag of fluid just behind the affected eye. At this stage, your fish will still be swimming about as usual, as the eyesight is not yet affected. But left untreated, popeye that has reached this level of severity will only get worse. 

Eyes Appear Cloudy or Discolored 

Another sign of popeye in your fish can be a discoloration of the eye. Again, this could be one eye or both. A healthy fish will have clear, bright eyes, free of any color spots or patches. 

If instead, the eye starts looking dull and faded, this could be a sign of popeye, even if there is minimal or no swelling on that same eye. A fish suffering from popeye could also have eyes that look cloudy, almost milky.  

However, it’s important to know that a discoloration of the eyes could also be a symptom of other problems and diseases in fish, especially if there is no accompanying swelling. If in doubt, it helps to ask a more experienced person to take a look, or even just take your fish to see a vet. 

Eyes Appear Bloodstained 

Sometimes, on top of the protrusion, a fish suffering from popeye will also have some bloodstains in the affected eye. It is easy to see, as it is impossible to mistake the color of blood for something else. 

Bloodstains in the eye are usually a result of extreme swelling. The bag of fluid behind the affected eye gets so big; it starts rupturing the blood capillaries in the area. Some of this blood then seeps into the cornea itself. 

It’s also possible for a bloodstain to result if your fish has got a severe physical injury to the affected eye. If that is the case, there may not be any swelling to speak of, or it could be minimal. Instead, the blood is a result of something scratching or piercing the eye. 

Eye is Ruptured or Falls Out of Its Socket 

It is the final stage of popeye, and at this point, there may be little you can do to salvage the situation. When the swelling bag of fluids behind the eye is left unchecked, it gets really big and builds up a lot of pressure. 

Eventually, the pressure gets too much, and the eye simply ruptures to release this fluid. If popeye has managed to get this far, there may not be much you can do to save the affected eye. With proper care and treatment, it has good chances of healing but will remain blind. 

Sometimes, the fluids building up behind the eye make the swelling so bad the eye just literally pops out of its socket. If this happens, the eye is lost completely, and there is nothing you can do to restore it. A fish affected to this point may also be really weak after the ordeal and die.  

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How Do You Treat Popeye? 

As we’ve seen, popeye can be the result of a variety of different causes. Whether your male goldfish got into a fight with another fish or whether your fish is suffering from a bacterial infection or some disease, there are ways to treat the condition. 

How to treat popeye in goldfish depends to a certain extent on the cause. Let’s look at the different things you can do to help your fish recover and get rid of the swelling and discoloration. 

Popeye That is a Result of Physical Injury 

If you’re sure that your fish has popeye because of a physical injury rather than a bacterial or parasitic infection, you may not need to seek veterinary care immediately. There are some simple steps you can follow to help your fish recover:  

You can begin by performing what is known as palliative care. Basically, you will be trying to improve the quality of your goldfish’s life and the environment in every way you can to reduce stress and speed up recovery. 

  1. To help the injury heal faster, add aquarium salt to your fish tank. You can buy this easily online or at any pet store selling fish and fish tanks. Salt can help to prevent parasites and bacteria from attacking your already weakened fish. But most importantly, salt will reduce the water pressure on the eye, reducing on your sick fishes’ discomfort. 

Take care to buy salt specifically designed for aquariums. Please don’t ever add table salt to your aquarium. Table salt contains various additives, such as iodine and anti-caking agents, that can upset the balance in your aquarium and harm your fish. 

  1. Change the water in your tank regularly. Even if you’ve been regular with your water changes before, it is especially important to continue doing so now, when your fish is sick. Changing the water frequently enough will help to remove impurities and prevent parasites and bacteria from multiplying. Your fish has a weakened immunity while it is trying to recover, and will be more susceptible to parasitic attacks in its weakened state. 
  1. Carry out regular water tests. It is the only way to be sure that your water has the right parameters for your goldfish. If your water tests show there is a problem, such as elevated ammonia levels or a drifting pH, you need to address it promptly. 

The best remedy for your sick fish is to make its environment as stress-free as possible to promote recovery. Correcting the ammonia, nitrite, and pH levels will give your fish the best chance of a quick recovery. 

  1. Feed your fish high-quality fish food. A good-quality fish food explicitly designed for goldfish will help boost your fishes’ immune systems. It will help your injured fish recover faster and help it fight off any parasitic or bacterial attacks on its system. High-quality food will also help to keep all your fish in good health. 

As well as this, it may be a good idea to stop giving your fish any treats for a while and stick to purpose-made fish food for a few weeks. It will ensure that your fishes’ diet is fully balanced, ensuring optimum health. 

Popeye Due to Parasitic or Bacterial Infections and Dirty Water 

If it looks like one or more of your goldfishes are suffering from popeye caused by bacteria (such as dropsy) or parasites, you need to take a different route to treat the affected fish and prevent any more fish from being infected.  

Dirty water also falls in this category. Dirty water itself will not cause your fish to develop popeye, but it harbors bacteria and parasites that will. So before taking steps to clean your tank water up, you’ll need to deal with the existing infection first. 

  1. Quarantine the affected fish in a separate tank. The first thing to do is to separate the affected fish from the others to prevent any further infections. 
  1. Treat the sick fish with broad-spectrum antibiotic food. Bacterial infections are notoriously hard to treat with antibiotics dissolved in tank water. Feeding your affected fish antibiotics through its fish flakes is much more effective. If you’re not sure what medicated food to go for, consult with your pet store supplier or vet. 
  1. It may be necessary to treat the main tank with antibiotics too. If more than one fish is showing signs of popeye, or if you notice more fish developing popeye a few days after isolating your first case, your main tank likely carries the infection. In this case, you’ll have to treat the main tank with a broad-spectrum antibiotic as well. Again, your pet store supplier or vet can advise you on the best product to do this. 
  1. Apply palliative care to both the quarantine and main tanks. Apart from giving your fish medication to treat the cause of the popeye, you’ll need to take the best possible care of your fish to help them recover. Change the water in your tanks regularly. Also, carry out water tests and correct any problems immediately to reduce on stress. 

Speak to your vet before adding any aquarium salt to your tanks. It may be contraindicated due to the antibiotic treatment your fishes are receiving. 

  1. If you’re suspecting a parasitic infection, have your aquatic vet perform a diagnosis. It can be done through skin and gill biopsy. Once the vet knows the underlying cause of the problem, they’ll be able to prescribe the correct treatment for your fish. 

Popeye Cause by an Internal Problem 

This can be the hardest to diagnose and will likely require an aquatic vet. If the cause of the popeye is neither physical injury nor a bacterial or parasitic infection, it could be an internal illness. 

Diseases like fish tuberculosis, kidney failure, and metabolic issues can all present popeye as one of the symptoms. There are usually other symptoms involved as well, however, and it’s up to your vet to make a qualified diagnosis.  

Apart from following whatever treatment your vet prescribes for your fish, the only other thing you can do is regularly carry out water tests and make the necessary adjustments, as well as change the water.  

(Other common problems with goldfish include dropsy, fin rot, ich, and constipation.)

How Do You Prevent Popeye? 

There are some things that can cause popeye, so there is no one-size-fits-all prevention method or cure. There are a few things you can do to reduce the likelihood of your fish getting popeye and any other disease.  

Feed Good Quality Flakes 

If your fish is eating food designed for its system, it will be getting the right nutrients in the right quantities. It will help to boost its immune system, making it less prone to parasitic and bacterial attacks. 

Good quality, the purpose-made feed also helps to prevent your fish from developing metabolic and other medical conditions, which are another cause of popeye.  

(Find out whether goldfish can eat tadpoles, bread, and bloodworms.)

Monitor Tank Water Chemistry 

Carry out regular tests on your tank water with the help of testing kits. It will show you if there is a problem, such as excessive nitrate levels or a wrong pH. You can then do the necessary to correct the issue, giving your fish the optimum environment to reduce stress and promote good health. 

Spend Time With Your Fish 

Regularly spending time with your fish is the best insurance against any kind of problem. If there’s a change in fish behavior, an injury on a fish, or something funny with the watercolor, you’ll notice right away and be able to sort things out. 

Perform Regular Partial Water Changes 

Regularly changing your tank water will help keep the tank clean and the environment optimal for your fish, not giving bacteria and parasites a chance to multiply.  

Don’t Keep Too Many Fish  

An overpopulated tank will result in your fish being stressed. Males will start fighting over territory and likely suffer physical injury in the process. It’s also a good idea to keep goldfish separately from other aggressive species that could chase and stress them out. 

Is Popeye Contagious? 

In and of itself, popeye is not contagious. But the underlying causes are a bit trickier. If the popeye was caused by a physical injury, it would not affect any other fish.  

But if it was brought on by a parasitic or bacterial infection, those same bacteria and parasites can spread through the tank, eventually affecting other fish too.  

Is Popeye Fatal? 

If noticed early on and treated accordingly, goldfish affected by popeye will usually make a full recovery.  

However, if the condition is allowed to go too far, it may rupture the affected eye, leaving it permanently blind. In some cases where the eyes rupture and fall out of their sockets, the fish do end up dying


Popeye in goldfish is not a disease but rather a symptom of some other problem. It can be a simple physical injury or a bacterial infection. It could even be some internal problem that your fish has, such as tuberculosis. 

Whatever the cause, popeye can usually be treated. If you follow the proper steps, your goldfish will usually make a full recovery. Check out the rest of our website for more tips on how to keep your goldfish healthy and all things fish-related.  

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