Goldfish Illness: What Are The Main Culprits?



White Spots

Bacterial Infection

Goldfish illness is very common and sometimes fatal. However, if the symptoms are detected early and correct treatment given, the goldfish can make a complete recovery.


goldfish ulcer treatment
maintaining good water quality is vital for healthy fish

Causes of fish illness can be bacterial, fungal, viral, parasitic diseases, physical ailments, protozoan diseases.


The most common maladies seen in home aquariums are either bacterial or parasitic in origin.


Fungal is sometimes seen and occasionally physical ailments.


When illness strikes your goldfish tank your fish may display behavioral symptoms such as:

  • clamped fins
  • body shaking
  • repeated scratching against the objects in the tank
  • gasping at the surface
  • hiding in corners
  • swimming abnormally
  • breathing difficulties
  • sitting on the bottom of the tank


These are caused by pseudomonas and aeromonas bacteria.

Symptoms are pinky-white open wounds and sometimes the fish has secondary infections caused by fungi and other bacteria. This is generally caused by very poor water quality or excessively high PH levels. It mostly affects newly imported goldfish.

Goldfish Ulcer Treatment: Test if the water has ammonia and nitrates. Change the water to reduce the pollution level. Goldfish lose a lot of salt quickly through their open wounds, so add salt to the aquarium at a rate of 2 to 3 grams per liter along with an anti-ulcer treatment.


Caused by bacterial infection, viral infection, nutritional and metabolic issues.

Symptoms are swelling of the body cavity due to a build-up of fluid. The scales become raised giving a pinecone-like appearance. Poor water quality, particularly the presence of ammonia and nitrates can aggravate the problem. This is confined to individual goldfish. It’s important to isolate the sick goldfish to prevent disease spreading to other fish.

Treatment: Test and improve water conditions immediately by adding aquarium salt at a dose of 2 to 3 grams per liter to prevent the salt loss. It can be difficult to treat and requires a broad spectrum anti-bacterial treatment.

One product I like and have often used is Tetra 8.45-Ounce AquaSafe Water Conditioner with BioExtract.

White Spot of fish

White Spots are caused by parasites infecting the goldfish.

The signs to watch for are small white spots on the skin, fins, and gills. The spots are about the size of a grain of sugar. It’s caused by stress related issues such as poor, incorrect water conditions, unstable water temperature and general poor husbandry. Sensitive goldfish may develop white spots as a result of being introduced to a new aquarium.

Treatment:  Ensure the water is free of pollution and isolate the cause of stress. Treat promptly with an anti-parasite medication. 2 treatment options are Malachite Green treatment or API’s Super Ick Cure.


Bacterial Infection

Caused by aeromonas and pseudomonas bacteria.

The symptoms are ragged fins with signs of infection, open sores, and reddening of the skin or fins. Bacterial infection is mainly caused by poor water conditions, especially the presence of ammonia and nitrates. Wounds may occur as a result of fighting or poor handling when transporting the goldfish.

Treatment: Improve the condition of the water and treat promptly with Melafix, an anti -bacterial infection remedy.

There are many other diseases that can affect your fish.

Poor water conditions and improper handling of the goldfish contribute greatly to goldfish illness. Early detection of symptoms and implementing the appropriate treatment is the most important thing you can do to provide the best outcome for your fish.

Diagnosis of the illness affecting your fish is an important part of overall goldfish care.

updated November 2018