A List of Goldfish Diseases

Goldfish DiseasesGoldfish for the most part are hardy fish that can survive in a wide range of conditions. However, if you don’t know how to care for your goldfish, the likelihood of it contracting one of the many goldfish diseases increases dramatically. The main cause of death in goldfish is due to improper care provided by the fish keeper.

Some of these common mistakes that lead to an unhealthy or diseased goldfish include the following:

  • High ammonia levels in the water due to infrequent water changes, too many goldfish in a tank or a bowl that is too small.
  • Constipation or a goldfish swim bladder disease that causes the fish to float sideways or upside down caused by overfeeding or a poor diet
  • Sudden death due to shock caused by a fast change in water temperature or pH when performing a water change.
  • A goldfish found dead on the floor due to a lack of a properly covered tank. If found in time, you can revive a goldfish out of water.

Technically the preceding are not goldfish diseases at all but rather health issues that are easily avoidable when regular maintenance is carried out. If however you do take good care of your goldfish and it still came down with an unknown illness, read the following information and accompanying posts to spot the signs and symptoms of the various health problems that can affect a goldfish.

Environmental Factors

Environmental factors such as poor living conditions can lead to health problems in your goldfish. Optimal water parameters will help avoid these types of illnesses but without testing the water, you might not even notice there are issues with your water. The following is a list of water parameters that should be tested and or adjusted to ensure they are within an optimal range that your goldfish will thrive in.

Water Parameters

  • Ammonia
  • Nitrates
  • Nitrites
  • pH
  • Oxygen
  • Temperature

Test kits are available to for the majority of these water parameters and there are also actions that can be taken to adjust them if they are off.

Goldfish Parasites

On first inspection of bringing your new pet home, you might not see any visible signs of parasites since they are microscopic organisms but you should always play it safe and assume they do have some sort of ailment. Parasites infestations are common among goldfish and one of the reasons that you should quarantine your fish before you place them into your existing tank. There are three main categories of parasites: ciliated protozoans, mono-genetic trematodes and crustaceans.

Goldfish Bacterial Infections

There are a number of bacterial infections that your goldfish can come down with. Bacteria are even more microscopic than parasites and thus can go unnoticed until the bacteria has a chance to take hold and your fish shows signs of an infection such as a goldfish eye problem. These tiny viruses can spread throughout the body of the goldfish, from fish to fish and even to human. If you provide good conditions for your goldfish to live, it will likely have a stronger immune system and in return will be less likely to become infected with a bacterial or goldfish disease.

Goldfish Fungal Infections

Fungal infections usually occur when a goldfish has open wounds, scraps or cuts that don’t heal quickly or those fish that have a weakened immune system due to poor living conditions and high stress. Most fungus infections look like white fuzzy hairs or cotton balls that appear on the skin, fins, mouth, gills or eyes of the goldfish. However, making a fungus infection diagnosis isn’t always easy with the naked eye since the visual signs look similar to some bacterial (columnaris) and parasite (Epistylis) illnesses. Water changes and aquarium salt are often included in a treatment of a funagal infection as well as a bacterial disease so this treatment is a good start if you don’t a microscope on hand to properly diagnose the problem. In cases where a fungus is caught early, it might be enough to just change the water and provide the goldfish with better nutrition. A healthy goldfish slime coat is also important.Common fungus infections include Branchiomyces and Saprolegnia. Branchiomyces is a fungus that attacks the gills and can be treated by lowering the water temperature and treating with Formalin. This fungus thrives in waters that are warm, have high nitrate level and organic loads. Saprolegnia comes about when goldfish are poorly handled, chilled or stressed. It can be treated by raising the water temps into the high 70s and given a formula of furazone green, methylene blue or malchite green.

Treating Goldfish Diseases

By reading all of our articles on the various goldfish diseases, you can find the treatments for curing them. Goldfish bath treatments can treat most illnesses and the information found in that article is a good place to start your treatment process.

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17 thoughts on “A List of Goldfish Diseases”

  1. Our 2 goldfish have red spots on them at the base of their fins & tail. It started after we introduced a new goldfish to the aquarium which died days after bringing it home. Now they also
    Have labored breathing & are having buoyancy problems. I switched out 40% of their water & treated the tank with 5 tablespoons API MELAFIX per 10 gallons. I also added 2 tablespoons of aquarium salt to the 10
    Gallon tank. I bought a ton of other treatments such as TETRA lifeguard & API body cure. If they are not
    Better tomorrow, which do you recommend trying next?

  2. I am facing the same problem.. I got 2 goldfishes. A few days ago, I saw one of them staying still at the bottom of the jar with its dorsal fin down. It’s tail now has turned red and looks like traces of blood.. When I had some goldfishes about a year ago, I saw the same symptoms in one of them. I searched in google but couldn’t find any disease that includes these kind of symptoms…

  3. we have goldfish in an outside pond. It has probably been there for 10 years or more. It was a small goldfish won at a fair. It is probably now about 5 inches long but has a very fat stomach, it looks pregnant? but cannot be as there are no other fishes. We do not feed it but the pond has other wildlife such as toads etc.
    Is the fish well? I could send a photo ? I cannot see any signs of it looking in poor condition but am only concerned that it’s stomach/centre part is very round and fat looking.

  4. I have 3 goldfish and they have been fine for the past 3 months and this past week everything changed all three have started staying still at the bottom of the tank with their top fin down and they all look like their color is foggy and the are bleeding around the edges I have never seen this can you tell me what to do before they all three die.

    • I am facing the same problem.. I got 2 goldfishes. A few days ago, I saw one of them staying still at the bottom of the jar with its dorsal fin down. It’s tail now has turned red and looks like traces of blood.. When I had some goldfishes about a year ago, I saw the same symptoms in one of them. I searched in google but couldn’t find any disease that includes these kind of symptoms…

  5. I just got a gold fish a couple weeks ago and just this morning I noticed his one while eye is blurry and white. How can I help him how can I treat this???

  6. I have an approximately 1000 gallon pond in our back yard with about 20 goldfish in it. Here in Cincinnati, we’ve had abnormally cold weather through April and I wasn’t able to restart the filter till about a week ago. I now have green algae (floating cells) in the pond, which usually is no biggie and the filter with UV takes care of it, however, I just noticed that one of my goldfish has the green algae on his body. 🙁 So far it only seems to be on the one fish. I have never seen this before nor could I find anything online about green algae on a goldfish. Have you ever heard of this happening? Any recommendations how to cure him?

  7. Hi. My son has a black moor fish. He is about 5/6 years old and he has one telescopic eye and one that has not only gone flat against his head but may even be slightly sunken. Do you have any idea why please?? Deb

  8. I have 7 goldfish. They are fantail. All seem pretty healthy, even the one I am asking about. I have a 55 gallon aquarium. I am running two up to 60 filters (without charcoal) they are hang off the back style. I have an air stick about 2 ft long. I change the water every 7 to 10 days about 60ish percent change and rinse the filters in aquarium water. My one fish Nemo I brought home from Walmart as a little guy about 2 ish years ago with 3 other goldfish with a 10 gallon tank and setup all in the same day. I knew nothing but learned quickly. I ended up going back to Walmart for water conditioner the same day. The salesman working didn’t warn me about cycling the aquarium or anything. At least the directions said to rinse the aquarium, rocks and add conditioner before adding fish. I was doing sometimes daily water changes until my aquarium cycled. All four survived and thrived, Thank God:) I feed them sinking pellets, peas, lettuce brine shrimp, krill and worms.

    Anyways, Nemo over time went from looking like Nemo to a peachy white. She has lost a few (about 3) scales that never regrew and from the tip of her nose to her tail she is smooth (no scales). Her fins are long beautiful and flowing. She has a great appetite. Her dorsal fin is perfect and up, not tucked. I just worry about the scales. everyone else seems fine. I change the water closer to every 7 days than 10. Sometimes 2x a week. I always clean the gravel when cleaning the tank. I did remove a log awhile back that may have had sharp edges. No one else had a problem with it. Any ideas why she lost scales? and should I worry about it or because everything else seems okay, just assume it was the log or something. I also leave the water level down an inch from the top to increase oxygen created by the filters. Hopefully this is nothing. But, I am worried. Thank you.

    Ps they have all grown a lot. The 3 new guys have doubled in size at least, and my 4 original fish have quadrupled in size, maybe more. Thanks again:)

  9. My goldfish is about a year and a half old and his mouth has been stuck open for the last few days.

    He LOOKS like he’s still eating–going up and gulping the flakes, but I don’t know if he’s actually swallowing. His mouth appears normal, just stuck. I have gravel in the tank, and he and his buddy do root around the gravel for snacks.

    Do I leave him alone? Take him to a vet? Pick him up and close his mouth/see if there’s something stuck in there??

  10. I have a goldfish 3 years old and some minnows. They have always lived happily together. My goldfish has developed a cotton wool substance on one of its eyes and is not eating. I have tried the blue dye treatment and aquatic salt but nothing clears it. The fish has now developed a sore on it’s side. It is still in with the minnows and they are fine. Anybody got any ideas?


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