Dropsy: Does your goldfish look swollen?

Dropsy is an extremely serious and often fatal condition affecting goldfish.

If you notice your goldfish looking fat, swollen or “about to explode” then the problem is probably dropsy.

Read on to find out more about the symptoms of dropsy, what causes dropsy and how to treat it.

Identifying and treating dropsy

How do you tell if your goldfish has dropsy? There are 4 key symptoms of dropsy to look out for:

(1) Extremely swollen belly that makes it look like your fish is very fat – possibly so fat that it almost looks ready to explode!

(2) Scales standing out like a pine cone

(3) Bulging eyes (one eye or possibly both)

(4) Swimming problems causing the goldfish to float at the top or sink to the bottom of the tank or pond

If you’re seeing swimming problems, but not the other symptoms, you should check out our article on swim bladder disease.

Fish with dropsy from above
Fish with dropsy on it's side

What causes dropsy?

Goldfish have a certain amount of salt in their bodies. This salt level is much higher than the level of salt in the water around them, which causes the fish to lose salt into the water and water to pass into their bodies. This is a normal process that happens all the time.

In order to maintain the salt levels they need to survive – and to avoid filling up with too much water – goldfish must continuously take in salt and expel water from their bodies. Again, this is normal and is a process controlled by the goldfish’s kidney.

Dropsy occurs when the kidney malfunctions. Your goldfish stops being able to get rid of all the water it is taking in from the tank or pond and instead starts to swell up like a water balloon.

Why does this happen? It could be any number of reasons. For example, infection that makes the kidney less efficient, an injury that allows more water into the fish’s body than the kidney is able to handle, or anything else that upsets the natural balance of water passing in and out of the goldfish’s body.

Can it be cured?

We’ll be honest; it’s very difficult to cure dropsy and in most cases it is fatal. By the time you see the symptoms, it’s almost always too late and very few goldfish recover.

Illnesses like dropsy are one of the main reasons why goldfish die.

However, there are steps you can take to give your goldfish some small chance of survival…

Treating dropsy

To give your goldfish the best chance of recovering from dropsy you should:

  • Set up a quarantine tank away from all of your other goldfish and add the affected fish
  • Try to keep the temperature of the quarantine tank around 25ºC / 77ºF
  • Use anti-bacterial medication, which you can buy in a pet store or online.
  • Add aquarium salt to the quarantine tank (use this calculator to work out how much salt to add – simply enter your aquarium size in gallons or liters, then type 0.7 into the “% salinity change” box, it will then tell you how much salt you need)
  • Remember to add more salt when you do a water change, as you will be removing salt from the tank along with the water
  • Keep the fish in the quarantine tank until all symptoms have disappeared and it appears fully recovered

Unfortunately, even fish that appear to recover may still relapse. It all depends on whether the kidney can repair itself during the quarantine tank treatment.

Dropsy is – sadly – a particularly difficult problem to cure.

If you’re not sure that your fish definitely has dropsy, we recommend researching the symptoms of swim bladder problemsconstipation and other goldfish diseases to find out what is wrong with them.

15 thoughts on “Dropsy: Does your goldfish look swollen?”

    • Hi Dave,
      Sometimes, while upsetting, it is the kindest thing to do, dropsy is a very long, stressful and probably painful way to die for a fish.

      Sometimes they can bounce back from bloat or dropsy given time, however, usually if they are swollen for over 2 weeks and are pineconing, sometimes they are too far gone, and putting your fish to sleep may be the best decision.

      You can tell a fish is in discomfort, as its skin will lose its colour, they will spend time alone and on the ground or up near the surface, and they will flap their gills rapidly.

      You can put a fish to sleep very humanely by using clove oil.

  1. My fancy goldfish turning black. she still eats but is down. Is in hospital tank. Condition started probably with adding water in the tank off temperature.
    Other fancy fish OK
    symptom #1 – blood in fins
    symptom #2 -fins spayed
    MelaFix then cleared
    Furan cleared
    Now nothing Hospital Water tested- was high in nitrates? Water changed

  2. My catfish belly is bloating even i put antibiotics and salt. Even after do frequent water change,no improvement

    • Hi Manira, thanks for your comment,
      I would highly suggest against using salt on catfish, as they are particularly sensitive to it, you can provide supportive care, increase oxygenation, fast them for a while, or even try feeding frozen peas as they are a natural laxative.
      The bloat could be caused by an obstruction in the bowels, they often pass these obstructions on their own, so it is best to provide supportive care, reduce stress and allow the catfish to pass it by itself, avoid doing water changes unless necessary, as this can be a key stress cause.
      good luck with your catfish, hope this helps.

    • Hi Kevin, thanks for your comment,
      Dropsy isnt really a contagious disease, as it can be caused by many things.

      the most common cause of dropsy is overfeeding or feeding the incorrect types of food which could clog the gut.

      if this case of dropsy is caused by an internal infection, while unlikely, it could possibly spread, however, it may not be directly linked.

      in short, dropsy is not contagious.

  3. My goldfish has had this for over 2 years and how it’s still alive is beyond me. I have done everything there is online but he still seems happy swimming about and feeding as normal. So hey can live a long time. I wish I could get him to a normal size though. ☹️

    • Hi Kaz,

      sometimes it is quite baffling to see what fish can live through and what conditions they can be subject to without dying, goldfish in particular are extremely tough given circumstances.

      We imagine dropsy as being an extremely uncomfortable and quite likely painful condition, as the fishes body is literally swelling with fluids much like lymphedema in humans.

      In cases we have seen, the fish show that they are under stress by losing colour, spending time away from other fish, breathing quickly and generally acting strange, although fish will always hide their pain well since they cannot make noise.

      some cases of dropsy affect the fish differently from others, in a lot of cases bloat is actually caused by colic (blockage in the gut) this will kill the fish fairly quickly in comparison.

      But things like fluid build up can last a long time without killing the fish.

  4. Hi, thanks for this article.
    I got my daughter some goldfish for Christmas, the first one lasted one month, the second died a few weeks later. There are plants in the tank, a filter and they were being fed flake food from pretty shop. I suspect dropsy as they both displayed pinecone scales and some bloating. The second one didn’t move very much the last two weeks and hanging around the surface a lot.
    Do I need to ditch the water and start again, or ok to give it a good syphon and then let it sit for a while (weeks?) before I reintroduce new ones? I tested pH and it was slightly alkaline but nothing crazy.
    Thanks for your help!

  5. My Ryukin goldfish keeps filling with water she is a deep belly Ryukin anyway but she is constantly filling with water. I am expressing her when I notice she’s filled up which makes me think it’s not dropsy because I’ve had goldfish with dropsy and couldn’t drain the water
    She’s swimming ok and eating. Anyone have any idea what to do? Thank you

  6. My fantail goldfish became very swollen and could swim normally but when it is still its goes on its side.
    I treated for swim bladder and fed it 1 pea everyday .
    The swelling went down and I thought great.
    But now the fish cannot swim normally and is constantly on its side one side slightly more swollen
    Today I have noticed red patches under its skin . It still eats with help from me but can no longer swim to the bottom of the tank

  7. My goldfish only seems to really have one symptom and that’s its pretty enlarged body. Still very active. Eating. Maybe its eyes are bulged some. Scales look pretty good. I bought kanaplex. It’s coming in the mail today. Any thoughts?


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