The 15 Most Common Goldfish Diseases (And How TO Cure Them)

For as hardy and resilient as goldfish are, these fish can quickly succumb to common diseases readily found in the home aquarium. Unfortunately, goldfish are often bred and stocked in poor conditions, leading to fish at pet stores becoming compromised. This sets the owner up for failure right from the start.

If you’re able to realize early on the signs and symptoms of disease and illness in your goldfish, then you can start treatment immediately and get your fish on the right track to living a long and healthy life. Otherwise, these sicknesses can be deadly.

Here are some of the most common goldfish diseases seen in the aquarium, how to diagnose them, and their respective treatments!

Key Takeaways

  • Goldfish are susceptible to many aquarium diseases, like ich, velvet, and dropsy.
  • Some of the most common diseases goldfish face are due to bacterial, fungal, and parasitic infections.
  • Some common symptoms goldfish display may need to be treated alongside the primary infection.
  • It is important to be able to identify the most common goldfish disease symptoms and have treatments available just in case.

The 14 Most Common Goldfish Diseases

Goldfish can contract the same diseases that most fish can in the aquarium hobby. For the most part, treatments for these coldwater fish are the same as they would be for tropical fish species.

In most cases, discoloration, lethargy, heavy breathing, and loss of appetite can be seen with any disease or ailment.

1. Ich

One of the most common aquarium diseases of all time, ich, plagues goldfish aquarium setups. Ich, scientifically known as Ichthyophthirius multifiliis, is a parasite that affects the gills, skin, and fins of fish. Left untreated, this parasitic infection can quickly lead to death.

Symptoms

Luckily, fish owners have discovered numerous treatments for ich that result in full recovery. The best way to treat ich is through prevention and early detection. Here are some of the symptoms you should look out for when adding new fish to your aquarium:

  • Flashing and scratching
  • Small, dispersed white spots all over the body
  • Heavy breathing
  • Discoloration
  • Lethargy
  • Loss of appetite

The most recognizable symptom of ich is small white spots that cover the entire body, leading to ich also being referred to as white spot disease. These white spots appear as raised bumps over the gills, skin, and fins. They are about the size of a grain of salt and can appear in clusters or more randomly around the body in any amount.

Treatment

While white spots are one of the easiest symptoms of ich to diagnose, the parasite can live undetected in the aquarium for extended periods. In fact, these parasitic infections can be transferred between tanks through shared filter media, substrate, or other decorations. Because of this, the entire tank must be treated, not just the individual fish.

Some of the most popular treatments for ich include:

  • Raising water temperature alongside frequent water changes
  • New Life Spectrum Ick Shield
  • Hikari Ich-X
  • Seachem ParaGuard

What causes ich?

Parasites cause ich, however, other environmental conditions can determine the severity of the outbreak. Factors such as poor water conditions and the current stress on the fish’s immune system can increase the likelihood of the fish succumbing to the disease. As messy fish that create a lot of ammonia, goldfish are especially susceptible to stress and subsequent disease.

2. Dropsy

Dropsy is another common goldfish disease, but is, unfortunately, not easily treated. While dropsy is usually referred to as a disease, this condition is more like a symptom of a greater underlying problem.

Symptoms

Dropsy displays itself as:

  • Swelling and bloating, especially in the eyes and abdomen
  • Outward pointing scales
  • Clamped fins
  • Curved spine
  • Discolored waste
  • Discoloration
  • Lethargy
  • Loss of appetite

In addition to these symptoms, the fish may also show signs of other common goldfish diseases that may be the cause for the onset of dropsy.

Treatment

Treating dropsy is difficult and most cases are fatal. However, dropsy isn’t contagious, though the underlying bacterial, fungal, or parasitic infections may be. Because of this, it’s best to remove the sick goldfish from the aquarium and continue treatment in a quarantine tank system.

Here are some of the treatments you can try to alleviate dropsy symptoms:

  • Frequent water changes
  • Epsom/aquarium salt bath
  • Seachem KanaPlex
  • Seachem MetroPlex
  • Fritz Aquatics Maracyn 2

I know both medications are not always available to some, so I’m going to defer to Lori’s Hartland’s experience on how she cured her Goldfish using a triple treatment of KanaplexMetroplex & Epsom Salt. Here is the full video below that walks you through her experience. It’s also very important to see her experience with her vet call at 19:06. She had to take a phone consultation, which is going to be what most will get when consulting a vet for a smaller fish.

What causes dropsy?

Dropsy is the secondary onset of symptoms caused by an underlying problem, usually a type of bacterial, fungal, or parasitic infection. The symptomatic swelling is caused by a dysfunction in the kidney or liver.

Because of the stress that the fish’s body is already under, antibiotics are only recommended if the underlying problem can be diagnosed as these medications heavily tax the liver.

3. Swim Bladder Disease

Another one of the most common goldfish diseases, swim bladder disease is challenging to treat but can be lived with. Like dropsy, swim bladder disease is often caused by an underlying problem, though it can be its own symptom.

Swim bladder disease, commonly referred to as swim bladder disorder, is a condition where the fish’s internal swim bladder organ dysfunctions. A healthy swim bladder allows the fish to regulate its orientation within the water column. A dysfunctioning swim bladder can cause the fish to swim upside down, on its side, or sideways.

Symptoms

Along with irregular swimming, the sick goldfish may show signs of:

  • Swimming upside down or sideways
  • Floating to the top of the tank or sinking to the bottom
  • Distended abdomen
  • Curved spine
  • Discoloration
  • Lethargy
  • Loss of appetite

Treatment

Treatment for these buoyancy disorders is straightforward, but not always guaranteed to work. In some cases, the swim bladder is deformed for life. If this happens, goldfish owners become very innovative and perform surgery or provide a wheelchair for handicapped fish that are unable to regulate their orientation.

Here are some of the best ways to treat a sick fish dealing with swim bladder disorder:

  • Fasting the goldfish
  • Feeding peas and sinking foods that prevent the fish from gulping air
  • Adjusting water parameters
  • Wheelchair

The last method of treatment you won’t hear much of on many blogs. However, it is a great solution for fancy goldfish. This can be created with airline tubing. The video above from Mark Kennedy shows how to create a swim bladder wheelchair.

What causes swim bladder disorder?

Swim bladder problems can come about due to primary parasitic, fungal, or bacterial infections. Any one of the other common goldfish diseases can cause stress and damage to the swim bladder, resulting in too much gas being created or distributed incorrectly.

Otherwise, the actual disease can be caused by the fish gulping too much air at the top of the aquarium. Irregular digestion from a poor diet or incorrect water temperatures can also cause the swim bladder to create too much gas. Internal injury can also cause permanent damage to the organ.

4. Neurofibroma

Neurofibroma

One of the less common goldfish diseases to see in the aquarium hobby, neurofibroma is a condition where tumors grow from the nervous system1. These tumors are often benign but can cause some discomfort as your goldfish tries to get around the aquarium.

In most cases, neurofibroma is no cause for concern. These tumors will often grow, fall off, and then regrow. While ugly to look at and sometimes uncomfortable for your goldfish, these tumors are usually not life-threatening.

Symptoms

There are not many symptoms of neurofibroma, but some things to look out for are:

  • Discolored, raised bumps on the skin and fins
  • Difficulty swimming

Treatment

While these benign tumors will usually manage themselves, surgical intervention is sometimes necessary. Veterinarians and fish specialists can biopsy the tumor and remove the affected cells. Therefore, the only successful treatment thus far has been:

  • Surgical treatment and removal

What causes neurofibroma?

It is not fully understood what causes neurofibroma tumors to grow. While some cases may be due to environmental factors, the major key component is likely genetics.

5. Rot (Fin, Tail, Mouth)

Rot-Goldfish

Probably the second most common goldfish disease to see in the home aquarium is rot. Rot can affect the fins, tails, and mouths of fish and lead to death in severe cases. Luckily, fin rot is very treatable and highly preventable.

There are two main types of rot, one caused by bacterial infections and the other by fungal infections. Sometimes, these can both happen at the same time and share many of the same symptoms.

Symptoms

Here are some of the most common symptoms to see alongside bacterial and fungal rot:

  • Clamped fins
  • Discolored and irritated fins and skin
  • Frail and fraying fins
  • Open sores
  • White, cottony growth for fungal diseases
  • Discoloration
  • Lethargy
  • Loss of appetite

Treatment

Treatment for these bacterial and fungal infections is easy and straightforward. Rot is not necessarily a problem within itself, but is often the result of poor water quality. However, most fishkeepers treat the symptoms alongside the cause.

Here are some reliable treatments for infected fish:

  • Frequent water changes
  • Aquarium salt bath
  • Fritz Aquatics Maracyn 2
  • Seachem PolyGuard
  • API MelaFix

What causes rot?

Simply put, rot is the result of goldfish living in poor water quality. Thousands of microorganisms live in our aquariums, some good and some bad. If the goldfish’s immune system is compromised or is physically injured, these microbes can enter the fish’s system, leading to fin rot or infection in other areas of the body.

6. Fungal Infections

The most common fungal infections arise from fin rot. Instead of bacteria infecting the open wounds or compromised sites of the fish, fungus, often from the Saprolegnia and Ichthyophonus genera, takes root and eats away at the fish. Cotton wool disease should not be confused with a fungal infection as those symptoms are caused by bacteria, namely Flavobacterium columnare.

Symptoms

It should be noted that a fungal infection does not necessarily indicate fin rot. Here are some of the symptoms that might appear on a fish’s body that’s struggling with fungus:

  • Cotton-like growth on the fins and body
  • Discolored grey or white patches
  • Ulcers and cysts
  • Discoloration
  • Lethargy
  • Loss of appetite

Treatment

Luckily, many medications target fungal diseases. Still, the best way to prevent and treat these outbreaks is by keeping aquarium water stable and clean. Here are some of the best goldfish fungal treatments available:

  • Frequent water changes
  • Aquarium salt
  • Fritz Aquatics Maracyn 2
  • API PrimaFix

What causes fungal infections?

Like a bacterial infection, fungal infections are caused by what’s already present in the aquarium. A goldfish tank is filled with good and bad organisms that will take advantage of a sick fish. However, some fungi are only able to thrive when dead and decaying matter is available. Once the dead fish, plant, or invertebrate has been removed and water quality improves, then the fish should start to get better.

7. Velvet

Freshwater Velvet

Velvet is a very aggressive disease and quickly causes sudden death for goldfish. This is another parasitic infection caused by dinoflagellate species in the Oodinium genus.

Like ich, these tiny parasite species live in the environment until they’re ready to attach to a fish. Once mature, they inject themselves into the fish’s slime coat. This infection eventually causes the gills and internal organs to inflame, leading to serious tissue damage.

Symptoms

Velvet is also commonly known as rust or gold dust disease due to its appearance on the fish’s skin. Here are the other ways you can diagnose velvet:

  • Fine white or rust-colored specks/coating that cover the body of the goldfish
  • Flashing and scratching against aquarium objects
  • Clamped fins
  • Abrasions and lesions
  • Heavy and rapid breathing
  • Discoloration
  • Lethargy
  • Loss of appetite

Treatment

Velvet is very difficult to treat because it progresses so quickly. If it’s caught early, then you may be able to save your goldfish. One of the best prescribed methods of beating velvet is by blacking out the tank by not allowing any light to enter as dinoflagellates are photosynthetic. Here are a few other ways you may help your fish:

  • Raise the water temperature
  • Create black-out conditions
  • Seachem ParaGuard
  • Seachem Cupramine

What causes velvet?

Velvet is a nasty parasitic infection that is similar to ich but more challenging to treat. This is caused by a photosynthetic dinoflagellate that has three life stages, including one that lives in the substrate, a free-swimming form, and one that requires a host in the form of a fish.

Because of this, velvet can easily be transmitted through sick goldfish or the transfer of aquarium media. The best way to prevent velvet is by observing new fish and using a quarantine tank.

8. Flukes

Flukes are very common among goldfish, especially fish that live in outdoor settings. Flukes, also known as trematodes, are types of external or internal parasites that can affect any part of the body. One of the most common flukes to diagnose is gill flukes, which are more difficult to treat.

Symptoms

Internal parasites can be more difficult to diagnose than external ones, but here are some of the warning signs:

  • Redness and inflammation
  • Flashing and scratching
  • Excess mucus secretion
  • Heavy breathing
  • Discoloration
  • Lethargy
  • Loss of appetite

Treatment

Goldfish suffering from flukes have a relatively high chance of survival as long as treatment is started immediately. Luckily, most of the aquarium treatments available are very effective, and it’s usually not necessary to use more than one method.

  • Aquarium salt
  • Seachem Paraguard
  • Hikari PraziPro

What causes flukes?

Flukes are parasites that are often carried into a tank on other fish and invertebrates. While they’re common to see in the aquarium setting, they thrive in outdoor environments. This is because most flukes require one or two more additional hosts, including birds and snails. This makes transfer from one outdoor system to the next relatively easy.

9. Anchor Worms

One of the easiest goldfish diseases to diagnose, anchor worms can be scary to see on your fish. These are a type of crustacean parasite that belongs to the Lernaea genus. Luckily, they are macroscopic external parasites that can easily be seen and diagnosed by the naked eye.

Symptoms

Here are some ways to tell if your fish has an anchor worm infection or not:

  • Thin white thread-like worms (sometimes Y-shaped) attached to the fish’s skin
  • Redness and inflammation
  • Lesions and abrasions
  • Flashing and scratching
  • Discoloration
  • Lethargy
  • Loss of appetite

Treatment

Treatment for anchor worms can take some trial and error. The best method is to move the affected fish to a quarantine tank, allowing the main goldfish tank to run empty, administering medications, and giving mild salt bath treatments. Here are some of the recommended treatments:

  • Aquarium salt
  • Fritz Aquatics Mardel Clout
  • Seachem Paraguard
  • Seachem Cupramine

What causes anchor worms?

Like other parasites, anchor worms can enter the aquarium via new fish or used plants and decorations. These parasites undergo several life stages, some of which are free-swimming, making transferral through different media very easy.

10. Ulcers

Ulcers are a big problem for the koi and goldfish industry but are often a sign of a bigger underlying problem. While not usually deadly on their own, ulcers can fester and become a breeding ground for bacterial and fungal infections.

Although ulcers aren’t contagious on their own, most fish exposed to those conditions suffer in one way or another due to environmental factors or secondary infections. The video by ThinFrog above highlights the aliment and how to cure it.

Symptoms

Here are some of the symptoms that might accompany ulcers:

  • Redness and inflammation
  • Open sores and lesions sometimes expose the muscle tissue
  • Cloudy and bulging eyes
  • Discoloration
  • Lethargy
  • Loss of appetite

Treatment

The first step to treating ulcers is finding the underlying problem. Most often, these abrasions come about due to poor water parameters, injury, or other stressors. It is key to treat those problems first, while also providing care to the wounds and preventing further infection from developing.

You can treat ulcers with:

  • Frequent water changes
  • Aquarium salt
  • API MelaFix
  • Fritz Aquatics Maracyn 2

What causes ulcers?

Ulcers can be caused by any one of the common goldfish diseases on this list. They are often the result of poor water quality, but they can be caused by a previous injury that hasn’t healed properly. Ulcers are often worsened by secondary infections and other goldfish parasites.

11. Carp Pox

One of the less common goldfish diseases, carp pox is mainly seen in koi. This disease is caused by the herpesvirus, also known as the Cyprinid herpesvirus 1 (CyHV-1). As a herpesvirus, symptoms can lay dormant until a certain stressor arises.

Symptoms

Many hobbyists are unfamiliar with carp pox and you might not even know your goldfish is a carrier, so it’s important to be able to identify these symptoms:

  • Moderately sized milky bumps and lesions on the skin
  • Bumps around the mouth region
  • Thickened skin around the fish’s fins

The good news is that carp pox is very survivable as long as a secondary infection doesn’t develop. At the same time, it’s safe to assume that all fish housed with a carrier of carp pox have been exposed to the virus.

Treatment

Unfortunately, there is no treatment for Cyprinid herpesvirus 1 (CyHV-1) and the fish will have the virus for the duration of its life. Raising the water temperature and keeping water parameters good can help bolster your goldfish’s immunity and help deter outbreaks.

What causes carp pox?

Carp pox is caused by Cyprinid herpesvirus 1 (CyHV-1). Fish become infected when the virus sheds off the skin of the infected fish into the water column and the system of another fish.

12. Cloud Eye

Cloudy Eye-Goldfish

Cloudy eyes are rarely a standalone symptom and often indicate a bigger problem at hand. While a cloudy eye may be the result of an injury to the eye, it’s much more likely that the fish is suffering from an underlying infection.

Symptoms

Along with a cloudy eye, your fish may experience:

  • Cloudy or opaque eye
  • Bulging or swollen eye
  • Difficulty swimming and navigating
  • Blindness
  • Discoloration
  • Lethargy
  • Loss of appetite

Treatment

A cloudy eye should be treated immediately to prevent the goldfish from losing its eyesight. At the same time, the underlying problem should be treated as well. This might include poor water quality or other internal infections.

Some treatments for cloudy eyes include:

  • Frequent water changes
  • Removing sharp objects
  • Aquarium salt
  • API MelaFix
  • Seachem KanaPlex

What causes a cloudy eye?

Cloudy eye is the result of some of the most common goldfish diseases, like the ones already on this list. Primary infections can cause the fish’s eye to swell and discolor as a result. However, a cloudy eye can also be due to an injury, so it’s important to get the correct diagnosis to proceed with the right course of treatment.

13. Pop Eye

Popeye Fish

Pop eye usually goes alongside cloudy eye (betta fish shown as I couldn’t find one of a goldfish). Again, this symptom is usually the result of an underlying problem, like an infection, though it can also be due to injury. The difference between pop eye and cloudy eye is that one or both eyes bulge out from the socket. The eyes don’t necessarily need to be discolored but often are.

Symptoms

Here are the main symptoms of pop eye:

  • Bulging eye or eyes
  • Disfigured eye socket
  • Cloudy or filmy eyes
  • Difficulty swimming and navigating
  • Blindness
  • Discoloration
  • Lethargy
  • Loss of appetite

Treatment

The treatments for pop eyes are usually the same as for cloudy eyes. It’s important to deter further infection from developing and to figure out the problem at its core. Here are some of the recommended treatments for pop eye:

  • Frequent water changes
  • Removing sharp objects
  • Aquarium salt
  • API MelaFix
  • Seachem KanaPlex

What causes pop eye?

Pop eye is most often the result of poor water quality or injury to the eye. Bulging eyes can also come about due to a primary infection, like a parasitic or bacterial infection. Pop eye is often accompanied by cloudy eyes.

14. Bacterial Infections

Our aquariums are filled with bacteria, some good and some bad. If a goldfish is compromised due to stress, injury, or other disease, then bacterial infections will take hold. You can see an example of a bacterial infection from the video by Aquafish Groomer above.

There are many different types of bacterial infections, and some can cause secondary symptoms that will also need to be addressed. It should be noted that a bacterial infection can develop due to one or more of the goldfish diseases on this list.

Symptoms

Here are some of the most common symptoms of bacterial infections seen in goldfish:

  • Clamped or frayed fins
  • Difficulty swimming
  • Redness and inflammation
  • Discolored or swollen eyes
  • Abnormal feces
  • Discoloration
  • Lethargy
  • Loss of appetite

Treatment

With careful attention, most hobbyists can narrow down the bacterial infection they’re dealing with so that they can use a specific medication. In some cases, it may be necessary to use a general antibiotic. Some of those include:

  • API E.M. Erythromycin
  • API MelaFix
  • Seachem KanaPlex
  • Fritz MetroCleanse

What causes bacterial infections?

There are many reasons why a bacterial infection might develop in a fish tank. The main reason is due to a compromised immune system, either due to stress, injury, or another disease.

General bacterial infections can be difficult to treat and it’s best to narrow down the specific type of bacteria you’re dealing with as best as possible. For the most part, though, bacterial infections are not contagious by themselves.

15. Constipation

Constipation is embarrassing but is one of the most common goldfish diseases to treat. Luckily, constipation is pretty easy to treat as long as you give some extra care and attention to your fish.

Symptoms

It might be difficult to tell if your fish is constipated, especially if it’s still asking for food. More food will only cause more damage, so keep a lookout for the following symptoms:

  • Less frequent waste production
  • Discolored feces
  • Abdominal bloating/swelling
  • Buoyancy disorders
  • Lethargy
  • Loss of appetite

Treatment

Once you’ve realized that your fish is having difficulty passing waste, treatment is relatively straightforward. Luckily, constipation doesn’t usually require medication treatment.

Here are some ways to relieve your fish:

  • Epsom salt bath
  • Fasting
  • Feeding peas
  • Dietary adjustments
  • Increase water temperature

What causes constipation?

Like other animals, goldfish constipation is largely due to improper digestion. This can be the result of a poor diet that doesn’t meet dietary needs or overfeeding. It can also be due to digestion tract dysfunction, which could be indicative of unfavorable environmental conditions.

FAQs

How do I know if my goldfish has a fungal infection?

The most common symptom of a fungal infection is spider-web, cottony growths that develop on the exterior of the body. This should not be confused with cotton wool disease, which is caused by bacteria.

What does a bacterial infection look like on goldfish?

A goldfish bacterial infection can look like a lot of things, but some common symptoms include redness and inflammation, cloudy eyes, clamped fins, lethargy, and loss of appetite.

What is the virus in goldfish?

Carp, including goldfish and koi, are susceptible to the Cyprinid herpesvirus 1 (CyHV-1).

How do you deworm goldfish?

Though goldfish are unlikely to carry worms, and you are even less likely to diagnose internal worms, a general anti-parasitic medication should help relieve worms.

What are the visible parasites on goldfish?

The most common visible external goldfish parasites are ich, velvet, flukes, and anchor worms.

How do I know if my goldfish has parasites?

Some parasites are visible, like ich and velvet. Some smaller flukes are impossible to see with the naked eye, so you should keep a look out for other common parasitic symptoms, like flashing and scratching, discoloration, and labored breathing.

Final Thoughts

Goldfish are hardy fish but are susceptible to aquarium diseases just like any other domesticated species. Some might say goldfish are especially likely to contract deadly illnesses due to the poor conditions and water quality they’re usually kept in. It’s important to be able to identify the symptoms of some of the most common diseases and have medications on hand when and if the time comes.

Otherwise, make sure to quarantine all new fish and invertebrates to guarantee the most success.

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