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Dropsy in Koi Fish

Dropsy in koi is not a disease, but rather the result of some other cause. There are multiple possible reasons; the most common cause of Dropsy in koi fish is from a bacterial infection that has gained access to the kidney and or liver through the blood stream. An alternative method of contracting Dropsy is brought about by a rare fish parasite that attacks the kidney, Mitraspora cyprini. Either way, kidney enlargement and loss of function ensues, eventually ending in kidney failure. Fortunately, Dropsy normally affects just one Koi at a time rather than an entire collection.

The Aeromonas or Pseudomonas bacterium is usually the culprit behind a bloated koi with bacterial dropsy. Parasites penetrate and damage the skin of a fish then the bacterial infection sets in. Pinecone disease or Dropsy is usually the final stage of the bacterial infection. The bacterium attacks the fish’s kidney and it stops functioning properly. The victim of Dropsy cannot expel fluids normally so it builds up inside the fish’s body. The pressure from the accumulating fluid causes the body to swell and this expansion causes the scales to stick out away from the body resembling a pinecone.   The affected fish’s head does not swell because of the bone structure, but the eyes may bulge or pop out because the excess fluid has no place to go.

Dropsy is also known as bloater or pinecone disease because of the symptoms exhibited by infected fish. In the advanced stages of Dropsy, Koi may lose the ability to maintain balance in the water because its swim bladder also experiences increased pressure from the accumulation of fluids within the body cavity.  

The condition of Dropsy in koi is very distressing to the koi owner. Not only does it look to be very painful for the fish, the fact is that most cases will be fatal. Because, by the time external symptoms are recognized, irreversible damage to the kidney has already occurred and the organ has been injured beyond repair or treatment.

In mild cases of the koi illness, Dropsy can simply be due to fluid retention. In this instance the use of salt can promote the release of the accumulated fluid and the Koi may be saved. Identification of such fluid buildup must be realized prior to the onset of any bacterial infection if the fish has a chance of surviving. Unless Dropsy is caught in the very early stages, a cure is almost impossible. 

Is Koi Dropsy Contagious?

No, Dropsy in koi is not contagious; however the circumstances that caused it usually are contagious. The most common cause of Dropsy is damage caused by parasites, followed by bacterial infection, and culmination in Dropsy.

What are koi Dropsy symptoms?

If suffering with Dropsy koi fish will exhibit the following symptoms:
  • Swelling of the body (fluid retention) 
  • Protruding or bulging eyes
  • Raised scales (pine cone appearance)
  • Lose of equilibrium/balance (swim bladder affected)
  • Isolation or staying in areas of high oxygen concentration