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The Goldfish are comparatively hardy species that live for over ten years in captivity. This however does not mean that this species cannot live being that age since there are some that have been reported to have lived in a home tank for around thirty years. However, this happens when the fish grows under maximum care and does not encounter some of the life-threatening common diseases that end up shortening their lives.  So there is a need to evaluate some of these common diseases and what causes them and how to prevent them.

Pogrebnoj-Alexandroff, CC BY-SA 3.0, via Wikimedia Commons

In this guide, we are going to discuss some of the common goldfish diseases and their causes, symptoms and the remedy to treat them.

These fish despite the fact that they are robust, are still very sensitive to the water conditions and the environmental factors within their home whether a tank or a pond. This, therefore, means that if your goldfish looks sick, this could be either there is a problem with the tank’s conditions. Thye could be;


The Goldfish are dirty fish species that emit a lot of bioloads. Therefore, if you do not maintain a high level of cleanliness by removing the waste regularly, the waste can easily accumulate and cause a lot of pollution to the aquarium water.  This will cause a spike in ammonia and it will be deadly to your Goldfish. To keep the tank clean and safe for your Goldfish, you need to carry out water replacement on weekly basis. You can choose to change either 10 or 20 percent of water in the aquarium.

During the deep cleaning of the gravel, you can use the aquarium vacuum and this will enable you to remove all the solid fish waste and decomposing debris from plants, and uneaten food before it has a chance to degrade.



This is a parasitic disease also known as White spot disease.  The white spot of this disease itself is not the parasite. It is usually the fish skin that is stretching over the parasite. This disease mainly occurs to the species when they are weakened, stressed, when kept in poor water conditions or when they are not first quarantined before being added to the tank. This disease can easily kill the fish if left untreated.


  • White spots resemble the salt granules covering the fish from nose to tail.
  • Clamped or flattened down fins
  • Darting and scratching against the walls and other objects in the tank.
  • Irritation
  • Breathing hard
  • Lethargy

If you see your fish showing these signs it may be a case of an inch and you need to take the necessary action and consult a vet. However, you should note that not every fish that has contacted the ich has white spots; some might just have behavior symptoms. Also, note that not every fish has white spots and has ich. Therefore, you need to consider other symptoms and behaviors to come to a conclusion that your fish has this disease.


Most commercial treatments are not able to eradicate this disease completely. However, there are some other means that can be used against ich. They involve;

  • Salting the tank by adding the recommended amount of salt  dissolved in water
  • Raising the temperature of the tank aquarium water up to about 80 degrees F. is important in speeding up the inch life cycle. You can also wait for 10 to 14 days and keep the water pristine.

If you want to prevent this disease in the future ensure that you do not share the tank equipment such as nets or siphons you have more than one aquarium since the ich can live outside the water and will get transferred to the other tank.

Also, ensure that every time you have a new fish you first quarantine it for some time before adding them to the main tank. This ensures the fish is healthy to avoid spreading the disease.


The fish lice are mainly found in ponds as compared to aquariums.  However, if you have a fish in your indoor tank that has been brought from outside you might find this disease in your tank. It is usually a crustacean parasite that lives by sucking blood from your goldfish.  Thye easily spread if they are not dealt with before getting out of control.


  • The goldfish might scratch and hitch themselves, leaping and darting around in irritation.
  • These parasites are visible little green specks and they have a shape of disc. Thye usually appears on the stomach, around fins, and chin.
  • When the case becomes severe you might find some red wounds on the body.


This disease is very resistant to most treatments. The salt will not work for this perky parasite.  This disease looks more like the anchor worm in that it responds to cyromazine. If you do not want to have lice in your tank, ensure that you quarantine all the new fish before getting in your tank and treat them for parasites ahead of time.


The fluke is one of the most common parasitic diseases found in Goldfish.  In fact, it is advisable that once you have bought the Goldfish from a pet store, assume that it has flukes, both the gill and body flukes. This parasite clamps on tight to the skin with spiky hooks and fee on the slime coat. This causes the fish to bleed constantly until it eventually dies.  One carry thing about these flukes is the fact that you cannot see them with naked eyes unless using a microscope.

This parasite bites the fish and injects the bacteria into your fish body and this is what causes the problem. However, despite the fact that you will need the microscope to know whether your Goldfish has flukes, you can also notice the symptoms.


  • Shedding on their slime coat and trying to get rid of themselves of the pests.
  • The fish will rub their fins sometimes bashing themselves on the walls and floors of the tank as they try to scratch.
  • The fish gets very thin sometimes.
  • The fish does not want to be around  other fish and clamps their fins
  • The fish usually has breathing difficulties and therefore they gulp at the surface.


Most of the parasites in the tank can be treated using salt but there are always those that will be least and the fluke is one of them.  They are generally salt resistant.  This, therefore, means that you are going to bring out the big guns and get your fish some strong anti-parasite medications. It is advisable to avoid the use of chemical-based medications such as formalin and praziquantel since they are very dangerous to your aquarium environment and the fish to live in it.

 Instead, the flukes can be treated using Minnfinn.  However, you can prevent this from happening in the first place. Do not wait for your fish to show signs in the future ensure that every new fish is treated for flukes unless they were treated by their previous owner. Always ensure that every fish is treated for these parasites before getting into the tank and this will save your fish.


Velvet is a parasite that is also known as Gold Dust.   This is rare in the goldfish.  This disease ticks on the fish with a long needle causing irritation and another symptom. This parasite is present in many tanks but becomes a problem when the fish is living in poor water conditions or stressed.


Below are some of the symptoms that a Goldfish will exhibit if having this disease;

  • Lethargy
  • Fish rubbing or scratching against walls and other objects in the tank.
  • Labored or poor breathing
  • Poor appetite and eighth loss
  • Film that is Yellow colored Fine rusty over the skin and this gives the fish a velvety look.
  • Clamped fins
  • When the disease is in advanced stages the fish skin starts to peel off.


The velvet cannot be completely fought by salt. That is why it is important to use something stronger such as copper.  The velvet parasite depends on light to live.  Therefore you might also deal with it by covering the tank with black paper or cloth to block out the light for some time. By doing this there is a high likelihood that you will have eradicated this parasite from your tank completely. However, the best way is to prevent this by quarantining every new fish before adding them to the tank.

You can use the copper sulfate for about 10 days in your tank.  As you treat the tank ensure that you remove your carbon filter also small invertebrates and snails should be removed since they are highly sensitive to copper.


Just as the name suggests, this disease is very dangerous. The Goldfish that have wen such as the lion’s head is prone to this infection more.  This disease is sonorous since it can spread from the outside of the fish to the inside and then the internal organs get damaged. This will consequently cause death.

This disease is also caused by stress, poor water conditions, and nutritional deficiencies.


  • This disease begins as a small red dot or bloody patch on the head and this is mostly above the eyes.
  • The affected area starts to sink deep over time pitting and spreading to cause multiple holes.


If you find out that your Goldfish has this disease then there is a high likelihood that your water is in bad condition.  It is important to ensure the environment the fish is living in is always in good condition because treatment will be of no help if that is not sorted. Therefore once the quality of water is high you can treat them by

  • Swabbing the hole with hydrogen peroxide once.
  • You also need to tat the fish with Metroplex since the Hexamita parasite is at play.
  • You can also use the antibiotics Furan 2 and Kanaplex together.

You can prevent the disease by

  • Keeping the tank clan
  • Avoiding overcrowding the fish in the aquarium
  • Changing aquarium water on a regular basis.


Fin Rot is another bacterial infection that attacks the Goldfish. Just like the ich, this disease comes when the fish is subjected to stress and living in poor water.  Just this disease is different from the ich since it is very stubborn and can take a while before it gets eradicated completely. If you let this disease go untreated for long, the fish might never grow back.


  • The fish can sometimes erode to the base of the tail
  • The rot starts out as a cloudiness in the fins
  • Fins get white on the tips and begin to rot away.
  • As the disease  takes hold the fins get shorter after the dead tissues fall away
  • Sometimes the bloody areas appear exposing the fish to other infections.


Despite this disease being dangerous the fish can be saved if it is realized in time and acted upon immediately.  One of the main challenges of treating your fish against this disease is the risk of burning your fish with medication.  This will make the problem worse and this explains why it is not recommended.

When it comes to treatments there are other alternatives. One of them is a hydrogen peroxide swab which offers a much safer route than medication. The affected areas should be dipped in hydrogen peroxide every 24 hours. Also, the MinnFinn can stop the rot on its track. However, if the disease is in its advanced stages, you might need an antibiotic such as Sulfaplex to save the fish.

If everything starts to work you will see black on the rotten areas instead of white and this indicates that the fish is healing.  It is, however, more important to prevent this disease than treat it and that is why it is important to avoid finding your fish living in poor-conditioned water. Always ensure the quality of your aquarium water is not compromised.


Ulcers are large red body sores that start off as a patch of red. They can quickly get larger and deep. It is believed that the main cause of ulcers is the flukes and they do so by injecting bacteria in the skin and it is very dangerous. You should be beware that if it is left untreated it spreads into the body organs. The bacteria are known as Aeromonas, Pseudomonas or vibria.  Also, this disease is associated with stress, poor quality water, and physical injury.


  • Sometimes the scales may prickle around the area.
  • The ulcers may start as an irritated-looking patch of red on the body.
  • The ulcers can also occur on the head of the fish often on the ones that have wens
  • Other fish may start nabbing at the wall and making it worse
  • The bloody hole becomes visible with time and it continues to spread and is sometimes bordered with pieces of hanging skin.


The ulcers are bacterial in nature and therefore they should be treated as such. They are however very dangerous to the fish and can easily kill them. The best approach to this is by;

  • Changing the water since your fish cannot recover in a condition that is not perfect.
  • Treat with the MinnFinn and ensure that you follow all the instructions as indicated.
  • Scrub the ulcers with hydrogen peroxide on a cotton ball.

It might take some time to improve and if not done well this may get worse. Therefore, if you overreact to this disease it can stress and kill your Goldfish easily. It is therefore advisable to avoid short gun treatments and instead stick to the plan.  An ulcer that is healing may look darker initially but as time goes it gets lighter.  To perfectly prevent the ulcers ensure that you treat your fish from flukes before adding them to the tank and maintain the water quality always.


Dropsy is a common Goldfish disease that happens when there are too many fluids in the body. Just like the pop eye, this is a sign of an internal problem and not the original problem itself. If you find your fish having dropsy in most cases then there is a problem with water or the diet you are feeding to your fish since these are the common causes.  When the fish is subjected to poor quality water, it makes the fish prone to bacterial infection. Bad diets will ruin the internal organs and hence they are in charge of the body fluids.

In some cases, the main problem might be some parasites inside the body of the fish.  Other common causes of this disease include temperature shock, tumors, and egg-binding.


  • Swollen abdomen
  • Curved spine
  • Lethargy
  • Swimming at the surface
  • Red and swollen anus
  • Protruding scales give the goldfish a pinecone like look
  • Pale and stingy feces
  • Bulging eyes
  • Loss of appetite
  • Red patches on the skin and fins
  • Clamped fins
  • Ulcers along the lateral line
  • Pale gills


Dropsy is a deadly disease and mainly, and by the time you realize the fish has this disease it is usually too late. This is because most likely there has been internal damage and once the internal organs have been destroyed there is nothing that can be done to avert that problem.  However, the fish may last for a few days or even months if you are lucky before it dies.  This disease and pop eye are terminal to the fish.

Due to the high death rate as a result of this disease, it is better to opt for euthanasia rather than treatment. The treatment of this disease becomes very hard to succeed in since no one knows this cause since it is a result of another internal problem.  Dropsy is caused by bacteria infection and therefore, antibiotics will be useful in treatment.  Also, the pressure as a result of fluid buildup may be eased by Epsom salts. Treating is not the ideal solution but maintaining quality water in the tank will do.


Mouth rot might either be caused by parasites or bacteria. Irrespective of the cause this disease is very dangerous to the goldfishes.  If the disease gets into advanced stages the fish will not be able to eat anything and this makes it important to detect the disease early.  This is mainly caused by poor quality water and overcrowded tank.


  • Mouths beginning to get very red
  • Goldfish starts to rub its mouth on the sides of the tank or other equipment in the tank.

If these diseases continue to attack the fish the area in which the sighs had started showing will start to erode and the lips will finally come off and the mouth will cave off finally. This leaves a jagged hole only. You should not let the disease get to this point instead you should start treatment as early as possible.


Apart from ensuring that the tank water is clean, there are other treatments that have been used and proven to be efficient. They are the hydrogen peroxide swabs and MinnFinn. If you are in a situation that is between life and death you can inject them with antibiotics. However, if your goldfish has mouth rot that is at advanced stages even after treatment the mouth will be left completely damaged. The fish will no longer be able to eat and will starve to death therefore if your fish is in this situation, it is important to put it to sleep in peace.

This explains why it is important to detect this disease early and prevent it from getting to that stage. You should try as much as possible to prevent this disease from happening by maintaining the quality of aquarium water.


The Anchor Worm is a goldfish disease that usually happens as a result of a change in the seasons. This disease is highly contagious and can easily infect the whole tank. The fish do not have to get stressed out to get them.  A lot of damage can be done by the time you realize the fish is this worm.  In most cases, the fish is usually dead or too late to reverse the damage done to the fish. It is, therefore, important to diagnose this disease early.


  • Stick-looking worms poking out of it
  • Itching and scratching against walls and other declarations
  • The skin becomes very red and bloody where the worm is attached.


Every time you see a worm on the fish you can remove it using tweezers and then use hydrogen peroxide to clean the wound. This will prevent any infection of the wound.  This disease cannot be cured using salt or other common fish medications on the market.  The only anti-anchor worm medicine is Cyromazine. It is very effective and accessible to the fish keepers.

If you find one of the fish in the tank with this disease, you will have to treat every fish in there. Also to prevent the spread of this disease ensure that every fish you add to the tank is first quarantined for some time.


Naturally, some goldfishes have to pop eyes but to some, this may be an indication that the fish is sick and needs help. This is a common disease that most goldfish find themselves with.  When you find their disease it is a signal that something is wrong internally than the disease itself.  Mainly it means there is a bacteria infection inside the fish.


  • The eyes beginning to bulge outwards  from the heads surrounded by  gags of fluid
  • The eyes protrude more than normal
  • One or both eyes are effected
  • Pop eye is often accompanied by dropsy or  other bacterial infection
  • During this phase, the eyes may easily come off.


To treat this disease you can add some Epsom salt at a quarter teaspoon very 10 gallons. This can help in reducing pressure behind the eyes. Kanaplex is recommended in fighting the infection. Also, you should ensure that the fish is living in good quality water to prevent and treat this disease.


Fungus is seen on a fish that is weakened by stress, injury, and illness.  When a goldfish is healthy it will not have fungus. The fungus is of different types and they show up in different places.  However, they nearly all have the same symptoms and are treated using the same treatment.

Fungus is mainly caused by Overcrowding, high levels of ammonia in water, poor immune system, poor water conditions, and stress.


  • The fungus appears as greyish or white cottony growth on the fins of the fish around the mouth and head.
  • The fish cats droopy and may lose interest in food

When the fungus reached the advanced stages, its spreads to the skin and eventually into the muscles tissues and this will end up killing the fish.


During the treatment of the goldfish, it is important to have clean water in the aquarium and this will make the recovery process easier.  Ensure the water is not very cold too.  Also, you can use Pimafix which is a natural fungi medication and it will restore everything I order.  You can easily avoid this disease since you know the main causes.


This disease is also known as white eye and it is mainly found in fish with protruding eyes.  This is because they are mainly prone to injury and then infection by sneaky bacteria.  The injury that causes this disease could also be a burn from ammonia.


  • The fish begins to have foggy-looking or hazy eyes.
  • The fish might have seeing difficulties
  • The fish eyes might also change color to bloodshot.


This disease can be treated it a little fish-safe salt. Three teaspoons per gallon and perfect water conditions can clear up this disease completely.  To avoid this disease you should avoid using decoration that has sharp edges and always keep the water conditions clean.

This is a parasite that does not actually feed on your goldfish. This parasite stresses your fish and therefore you need to do anything to avoid them. This disease is common in dirty aquariums. A clean tank will get rid of them completely sometimes.



  • Scratching against objects and irritation
  • The fish might lose appetite and stop eating
  • Ulcers develop from so much itching.


The trichodia can be treated from the goldfish by the use of a high concentration of salt.  Using 3 teaspoons per every 10 gallons of water can work effectively.  However, this high concentration is extremely stressful to the goldfish.  You might end up killing the fish in an effort to kill the parasite. You can also use the MinnFinn however, the best thing is to prevent it from occurring from the beginning and this can be done by quarantining every new fish.


Costia is also known as Catastasis is a freshwater protozoa parasite that is known as Ichthyobod necatrix or Ichthyobodo pyriformis. This parasite latches onto the gills or the fish skin and starts feeding on the fish. This disease moves from one fish to the other as it reproduces and will spread quickly in a community aquarium.  They are mainly brought into the tank by a new fish.


  • Clamped fins
  • Resting on the grave
  • Lethargy
  • Excess production of mucus
  • Difficulty in breathing
  • General debilitation

As said earlier this parasite feeds on the fish’s gills and therefore, they can easily kill the fish by depriving them of oxygen. Remember they use gills for breathing.  Also as a result of skin damage to the fish, there is the likelihood of secondary bacterial and fungal infections to the fish.


This parasite disease can be cured by the use of commercial treatments such as Malachite Green, potassium Permanganate, or Acriflavine.  You can also use strong salt baths.


A tumor is created when the cells are multiplying out of control.  The goldfish get the tumors too and sometimes they can be cancerous.  They can also grow and get to unbelievable size.  They grow fast and multiply easily.  These tumors can be inside the body or the outside.  Some even blind the fish by blocking their eyesight. They finally may kill the fish if they are left untreated.


  • The growth may be pink, whitish, or even black.
  • A small lump starts to grow on the fish and it is mainly on the body or head.
  • The fish will sometimes lose appetite and not eat and appears depressed.


When the tumor is discovered earlier it might be easier to eradicate it. You can make the process easier by sedating the fish with clove oil.  Since some of the aquarists are not comfortable doing that you might need to get professional help from a vet.

Tumors can be caused by exposing the fish to poor water conditions and feeding them a diet that is laced with preservatives. To prevent the disease ensure that you always keep the aquarium water clean.  Some care is caused by a virus and you cannot help.


Swim Bladder Disorder is a collective term used to refer to a group of issues that affect the ability of a goldfish to swim in a normal manner. In the goldfishes, the round bodies species are the most prone to this disease. This disease occurs when the fish swim balder becomes compressed. Some of the causes include

  • Gulping air
  • Overreacting
  • Eating dried food
  • Constipation
  • Trauma
  • Bacteria infection

Also, this can sometimes be a result of birth defects but in such a situation the fish will rarely survive.


  • The fish is not able to swim upright on an even keel
  • The affected fish usually float on water or sink to the bottom
  • Sometimes you might find your goldfish upside down unable to put themself in the right position.
  • Distended belly
  • Curved spine


This disease can be treated by starving the fish for about 2 to 3 days and then feeding them frozen food or blanched skinned pea.  You can also deal with it by warming the tank water by a few degrees. If the cause of the disease is bacteria you can use the broad-spectrum antibiotic.


Just like most goldfish diseases, this virus attacks a fish that is weak and stressed. It is a viral disease that is caused by iridovirus.


The fish develops some irregular lumps over the head, tails, fins, or body. These lamps can be tiny white spots or large cysts that cover a large part of the body.

These lamps can be pale grey or pinkish and this explains the name cauliflower disease.


This viral disease can be treated by bathing the goldfish with a chemical known as acriflavine. If your fish is lucky the virus will disappear within a short period.  It is not well established how this virus disease spreads but it is important to prevent it by keeping the water clean always.


This is a common virus s among the goldfishes. It is common in the goldfish that are kept in ponds or sometimes in aquariums and it is not known how it spreads.  This disease might not kill your fish at the end of it all but it might disappear and appear later.


The common symptom of this disease is small lesions and a thickened skin. That resembles drops of a cuddle.


This disease has no exact cure. However, you can manage it by ensuring the aquarium water is always of high quality and by feeding your fish a nutritious and right diet.  You can also ease the symptoms by using slightly warmer water.

Sometimes this disease damages the fish’s skin so much that it exposes the fish to the risk of getting bacterial infections. You, therefore, need to be very keen.


This is one of the diseases that are regarded as dangerous ones since they are extremely difficult to detect.  Before you are aware of this disease in your goldfish there is severe damage to the fish tissues. Just like most parasites this parasite gets into the tank when a new fish is introduced.


  • Flushing and rubbing against the wall of the tank and other objects.
  • Resting at the bottom of the tank
  • Difficulty in breathing
  • Lethargy
  • Fish Hanging on the water surface
  • Clamped fins


  • This fish can be treated by using commercially prepared treatments such as Potassium permanganate, Acriflavine, and malachite green.

Rubbing the body against objects might expose the fish to bacterial infections.


From this guide, you can conclude that most of these diseases are a result of poor water conditions. It is, therefore, important to maintain weekly water changes, vacuum the gravel and manage the filter correctly so that the water conditions can always be at the optimal level. This will help the fish to fish to always remain safe and keep all the viruses and parasites out of your tank.

Also, some diseases are brought in by the new fish. It is, therefore, important to have a separate tank where every new fish will go through quarantine before being added to the main tank. This will give you an opportunity to ensure the fish is free from any disease and then can be added to others. It is our hope that the guide has been of great impact in educating you on the diseases and how to deal with or prevent them.

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