7 Diseases That Affect Goldfish

Three goldfish in a tank with plants and rocks

Many illnesses can affect goldfish in freshwater. If you own a goldfish, you should be aware of the following illnesses and conditions:

Poor Water Quality

The most prevalent cause of sickness in goldfish is poor water quality, which isn't exactly a disease. Goldfish are dirty creatures which quickly produce a lot of waste and filthy water. Poor water quality can result to chronic stress in inappropriate situations, such as ancient bowls or extremely overcrowded systems. A fish that is unable to flee a hazardous environment will become chronically stressed, resulting in a reduction in development, immunological function, and reproductive capabilities.

It's vital to provide your goldfish adequate room to live a healthy existence. Comet and other long-bodied goldfish will demand 20 gallons of water to begin with. As the fish develop, you'll probably need 50 to 75 liters per fish. Goldfish may grow to be 14 to 16 inches long, so expect that rather than 2 to 3 inches. No fish should be kept in a dirty dish. Goldfish do not require heaters, but they do require purified aquariums.

Regularly test your water quality and make any necessary adjustments. In many goldfish aquariums, feeding high protein flake food can be a major issue. Always feed your fish a pelleted diet that is the right size for them. If you're having difficulties keeping your water quality in check, get assistance from your aquatic veterinarian.


Bringing a fish home from the pet store is the most dangerous time for a fish to become infected with a parasite. Most parasites may move in water and on equipment, thus fish from various sources and exposures are combined in different systems at pet stores.

Missing scales, flashing, bruising, lethargy, and/or rapid death are all symptoms of goldfish parasites. The following are the most frequent goldfish diseases:

  • Ichthyophthirius multifiilis (White spot disease)
  • Trichodina
  • Mongenean trematodes ("Flukes")
  • Icthyobodo ("Costia")
  • Learnea spp. (Anchor worms)
  • Argulus spp. (Fish lice)
  • Chilodonella

A tight quarantine regimen is the best way to prevent parasites. Because there is no "one-size-fits-all" therapy for parasites, an accurate diagnosis from an aquatic veterinarian is essential for successful treatment. It's a recipe for disaster if you just assume and give your fish a handful of OTC drugs.



Comet goldfish, especially those maintained outside, are prone to these "lumps." Neurofibromas are difficult to cure because they develop from neural tissue deep under the epidermal layers. They frequently produce a "stalk" and then fall off, only to regrow. One or two lumps may be isolated or spread throughout the body of certain fish.

Recurrence makes treatment unnecessary. Multiple techniques, including surgery and freezing, have failed. It is not worth it to subject your fish to arduous therapy that will not address the problem. Because these benign tumors emerge from brain tissue, there is presently no medication that can directly target these tissues.

Buoyancy Disorders

Both negative and positive buoyancy problems can affect goldfish. They have a pneumatic conduit between their esophagus and swim bladder because they are physostomous fish, which allows them to consume air to inflate their swim bladder. The oval, a distinct gland, is in charge of eliminating excess air.

After eating, positive buoyancy problems are the most prevalent. Goldfish, the golden retrievers of the fish world, will frequently suck in too much air when feeding actively at the surface. Either the GI tract or the swim bladder will absorb it. The fish returns to normal when the extra air is removed. It has been known for the oval to malfunction, resulting in permanent positive buoyancy issues. These problems are frequently treated with surgery.

Stress or a bad diet are the most prevalent causes of negative buoyancy issues. Simply put, your fish lacks the desire or the energy to swim. They will return to regular behavior after the tension is relieved and they are fed properly. External "wheelchair" floats are exceedingly hazardous to your fish and can cause major injury.

Polycystic Kidney Disease


Goldfish are susceptible to an illness that causes cysts to grow in their kidneys, causing dysfunction and tissue damage. Unfortunately, no one knows what causes this sickness, and there is no cure. The kidneys, like those of many other animals, do not regenerate after they have been injured.

Polycystic kidney disease symptoms like a baseball, softball, or even volleyball being eaten by your fish. Despite their unusual look, fish may behave normally. Diagnostic ultrasound is necessary. Please do not pinch your fish! This can harm your fish's organs and will not aid them in any way.

Cloudy Eyes and Popeye

Poor water quality, trauma, and secondary illness can contribute to cloudy fish eyes. Some fish, particularly some luxury types, may have larger eyes than their counterparts, making them more vulnerable to harm.

Popeye is a prevalent online infection for which there is no cure. Eyes can become dilated as a result of a variety of secondary conditions, so visit with an aquatic veterinarian as soon as possible to determine the main reason and devise an efficient treatment plan before the eyes are gone.

Red Streaks on Skin and Fins

Stress and poor water quality can cause red streaks on the skin and fins. If you notice them on your fish, you should examine your water quality right away. Correcting it if it's off might help with streaky problems.

If your water quality is within range and no major changes have been recently made, it is critical to identify the stressor and remove it from your system.

Non Diseases

There are a few diseases out there on the internet that are technically not diseases. They are symptoms of many common fish diseases.



This describes the clinical condition when fluid collects between the scales of a fish and they look like a pinecone. It is a clinical sign of kidney or gill malfunction and is not a disease.

"Swim Bladder"

Yes, your fish has a swim bladder. "Swim bladder" disease can be many different things and requires a consultation from an aquatic veterinarian. There is no one cause of buoyancy disorders.


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