Dropsy in Freshwater Fish

Koi exhibiting typical dropsy appearance

What is “dropsy?”

Well, to start off, “dropsy” is NOT a disease. “Dropsy” describes a condition where a fish’s body balloons outward and their scales start to stick out, looking like a pinecone. This syndrome is caused by excess water in the body cavity or coelom. Excess water collects in the skin between the scales and around the internal organs causing the traditional “dropsy” appearance.

This presentation is merely a sign of poor kidney function. Freshwater fish live in an environment that is less dense than their bodies. Through passive diffusion, water is constantly trying to even out the fish’s density by pulling water into the body tissues, mainly the skin and gills. A freshwater fish’s kidney works very hard to remove excess water and pass it back out into the environment with other waste. If the kidneys are not functioning correctly, water is not removed effectively and the fish starts taking on water.

What causes dropsy?

Many different disease processes can cause this syndrome, including stress from poor water quality, inadequate diet, tankmate aggression, tumors, parasites, viruses and bacteria. “Dropsy,” or more clinically edema, is simply a sign that there is something wrong affecting the kidneys and not a specific disease process.

How can I treat dropsy?

When your fish takes on this appearance, don’t assume it will be corrected by dumping in antibiotics. Not only is this harmful to your fish, but it gives owners unnecessary exposure to the drugs as well. Not to mention that all OTC fish meds are not controlled or evaluated in ANY way. Start by checking your water parameters, evaluating your fish’s diet and making sure no on is picking on them. If you do not find a clear cause, contact your local fish veterinarian.

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8 thoughts on “Dropsy in Freshwater Fish”

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  6. Hi!
    I am Maria from Hungary.
    I am a human medical doctor & a crazy obsessed aquarist 🙂
    I am the administrator of the alphabet facebook group for aquaristics (Akvarisztika ABC), where more than 6,500 aquarists have gathered. Since I am editing the group’s website, I consider it my profession to write a reality about aquatic animal diseases on the website rather than a legend.
    It is OK, that the dropsy is a kidney or gill disease, but: what can I do, what can we do with the fish patient?
    I think we should isolate it first in a hospital aquarium. But what happens next? Disinfectants and good water quality? Vitamins? Obsession…?
    (Not antibiotics, that is clear).
    There is only one group of aquatic animals in Hungary (Vet4Fish). They are too busy to answer my questions.
    I really like your website, I learned a lot from your articles and videos.
    Please help! What should an aquarist do if he develops ascites (dropsy) in fish but no aquatic healer is available?
    Thanks for everything!
    Best regards: Maria from Hungary

    This is my aquarist website aquatic animal medicine part

    1. Dr. Jessie Sanders

      Since kidney and gill issues have very many causes, there is no one effective treatment. You may want to look into wavma.org for more aquatic veterinarians in your area.

      1. Unfortunately, this is a small country in Europe with a total of 3 fish doctors, they are the Vet4Fish. (They are fantastic anyway!)
        In this case, however, the only solution at the end of the article is for the aquarist to consult a fish veterinarian after examining and improving the water parameters and nutrition.
        That’s so fair, isn’t it?
        I don’t want another legend, I want to give correct information to Hungarian aquarists.
        Thank you for your reply and for your time!

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