How to Cure Goldfish Dropsy

Goldfish 'dropsy' disease technically isn't a disease but rather an internal bacterial infection often found in the kidneys of a goldfish. Dropsy disease causes the kidneys to retain body fluids and thus causing swelling of the belly of the goldfish. In late stages of dropsy disease, the scales of the goldfish will protrude outwards. When you observe these symptoms in a sick goldfish, its chances of survival are low. If dropsy disease is diagnosed early, goldfish can survive. Other symptoms include: lethargy, loss of appetite and a goldfish that in general doesn't look healthy.


  1. Image titled Cure Goldfish Dropsy Step 1
    Remove the sick goldfish from the tank and isolate it in a quarantine tank. Dropsy isn't typically contagious so there isn't a need to treat the entire tank. Treating an entire goldfish tank can be harmful to the healthy goldfish.
  2. Image titled Cure Goldfish Dropsy Step 2
    Add Epsom salt at 2-1/2 teaspoons per 10 gallons (37.9 L) of water. Epsom salt helps draw out excess fluid in the goldfish giving some relief to the sick goldfish. Epsom salt (magnesium sulfate) is different from most aquarium salt treatments (sodium chloride).
  3. Image titled Cure Goldfish Dropsy Step 3
    Add Maracyn or Kanamycin to the quarantine tank to help treat any gram negative bacterial infections.
  4. Image titled Cure Goldfish Dropsy Step 4
    Feed the sick goldfish an antibacterial food to assist in the dropsy disease treatment.


  • Goldfish are susceptible to infection when their stress coats are weakened by injury or stress. Add a protective stress coat product to encourage a healthy slime coat.
  • The best treatment for goldfish dropsy is to prevent it. Dropsy is the result of poor water conditions and improper tank maintenance leading to excessive stress of the goldfish . Preform regular water changes and optimize the water parameters including: temperature, elimination of chlorine/chloramine, pH, dissolved oxygen, and zero readings of ammonia and nitrite levels.
  • If dropsy treatments fail to work and symptoms continue to get worse, you can put a terminal goldfish out of its misery by using clove oil. It's considered the most humane way to kill a goldfish.


  • An overdose of Maracyn can be harmful to the kidneys of a goldfish. Kanamycin is the safer treatment.

Sources and Citations

  • Johnson, Erik DR., and Richard Hess. Fancy Goldfish: A Complete Guide to Care and Collecting. Boston, MA. 2001.
  • Brewster, Bernice. An Essential Guide to Keeping Goldfish. Surrey, ENG. 2003.
  • Boruchowitz, David. Aquarium Care of Goldfish. Neptune City, NJ. 2008.
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Categories: Fish Health | Goldfish