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.

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.

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

  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


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