Gosanke koi fish swiming in a pond

Dropsy (which is an old-fashioned term for edema) is also known as Pinecone, Bloater or Pop-eye disease. The fish’s pine cone appearance is a result of pressure from the buildup of fluid when the koi cannot expel water as quickly as it absorbs it. The extra fluid in the body causes the eyes to protrude and scales to stick out away from the body.

Sadly, dropsy has an extremely high mortality rate. It can be cured, but once the external signs are visible, the internal organ damage is already so widespread that there is little chance of a recovery.


The noticeable, external physical manifestations of the disease usually occur during the final stages of a bacterial infection. However, Dropsy can result from many internal causes that include:

  • simple fluid retention
  • kidney failure
  • congenital heart failure
  • bacterial infection
  • viral infection
  • parasite attack (Mitraspora cyprini)

The bacterial infection can be caused by the ever-present Aeromonas or Pseudomonas bacteria, which enter the bloodstream and are filtered through the kidneys and liver. If this opportunistic pathogen finds a foothold, it will eventually cause organ failure.

Dropsy causing pine cone appearance of koi scalesDropsy is usually restricted to one fish; however, if more than one fish is exhibiting dropsy, it could mean that a virus is the root cause. Thankfully, though, a dropsy virus is more rare for enthusiasts, as is the parasitic cause in Mitraspora cyprini.

Whether bacterial, viral or parasitic, it is primarily the kidneys that are affected. It is the infection that causes organ failure, which is the point when the symptoms of dropsy become noticeable.


The symptoms of full-blown Dropsy are immediately recognizable and in most instances mean the koi is almost beyond curing. The symptoms include:

  • eyes bulging out
  • distended (bloated) stomach
  • raised scales (so it looks like a pine cone)
  • gasping
  • unbalanced swimming (as the swim bladder is affected by the excess fluid, too)
  • appetite loss


The speed with which you diagnose and treat the symptoms can often make the difference. It is an extremely difficult infection to cure. As it is most often a bacterial infection, an anti-bacterial regimen is often the option used for treatment. The steps are:

  • isolate affected koi
  • raise water temps
  • increase oxygenation
  • use antibiotics (either injected or in feed)

The antibiotic regimen will differ between enthusiasts, and may include tetracycline, naladixic acid, penicillin or baytril.

Dropsy itself is not “contagious”; however, it can signal that your pond has bacteria or other infection-causing agents, and these conditions can affect other koi in the pond.

Although water conditions aren’t the root cause of Dropsy, keeping your pond low in nitrates with good pH will minimize the conditions that lead to infection. Some enthusiasts advocate for other preventative measures, like spring parasite treatment and higher amounts of antibiotic feed.

At Next Day Koi, we take the utmost care to minimize health issues in all of our koi fish for sale. This includes a rigorous 14-day quarantine protocol in separate tanks and close monitoring of all of our fish.

3 responses

  1. daniel chao :

    One Koi has dropsy and I tried to treat him having no results. I can not find a fish vet nearby. Can anyone have an idea what to do next? Where can I get the injection that seems to be the final solution?

    1. Hi Daniel, We are very sorry to hear that you are experiencing issues with Dropsy in one of your fish. You could try contacting one of your local Vet offices to see if they can send you in the right direction if they do not have the medication in their office.

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