Causes, Symptoms & Treatment Of Dropsy In Fish

A sick fish is something all of us will have to deal with from time to time. Dropsy is one of the more serious problems as it is often fatal if it's not identified and dealt with early enough.

There’s a lot of misinformation about dropsy in fish out there. In this post, I’ll cover the most frequently asked questions.

I’ll also share a treatment plan that has worked for me, so you’ll be in a much better position to deal with dropsy in your aquarium should you have to.

What Is Dropsy In Fish / Dropsy Disease

Despite its name, dropsy disease (also known as bloat or pinecone disease) isn’t a disease. It’s actually a symptom of underlying issues that are causing your fish’s gills and kidneys not to function correctly.

Fish are constantly taking on water through a process called osmosis. It’s the kidneys and gills’ job to get rid of excess water. When they’re not working correctly the fish retains excess water and starts to bloat.

Dropsy is the swelling of the soft tissue within the fish’s body, due to water retention. It causes a huge swelling of their belly and if left long enough their entire body. Their skin stretches and their scales start to stick out, making them resemble a pinecone.

Is Dropsy Disease Contagious To Other Fish?

Is Dropsy Disease Contagious To Other Fish?

Dropsy itself isn’t contagious as it is a symptom of other underlying issues. However, the underlying issue that has caused dropsy may be contagious.

You need to find out what has caused your fish to get dropsy in the first place, and then address the underlying issue to stop the rest of your fish from possibly getting it.

Can A Fish Recover From Dropsy?

If you spot the signs of dropsy early enough and take immediate action, it’s possible that a fish can recover from dropsy.

It’s not a quick recovery process and will require time and patience from you. You also need to be prepared for the worst as there is no guarantee any treatment will be successful.

If your fish has the late stages of dropsy, the prognosis generally isn’t good. Usually, euthanasia is the kindest thing to do.

Treatment of dropsy is generally geared towards correcting the underlying cause and preventing it from happening to your other fish.

Dropsy In Fish Symptoms

There are many symptoms of dropsy in fish. If you spend time watching your fish and get to know what’s normal behavior for them, you should then be able to notice when something doesn’t appear right with them.

There are some early warning signs that your fish could have dropsy including:

  • Appearing lethargic
  • Clamped fins
  • Curved spine – caused by internal organs being pushed aside
  • Hiding
  • Loss of appetite
  • Loss of coloration
  • Pale gills – a sign of anemia
  • Passing pale and stringy poop
  • Redness of the skin and fins
  • Swelling of the anus
  • Swimming near the water’s surface
  • Ulcers along the body and lateral line

The more advanced symptoms of dropsy are:

  • Swollen belly
  • Protruding scales that resemble a pinecone
  • Bulging eyes – known as popeye, this is a related condition caused by the Aeromonas bacteria found in an aquarium

A fish with a swollen belly can also be a sign of swim bladder disease.

What Causes Dropsy In Fish

One of the biggest myths I see a lot is that the bacteria called Aeromonas causes dropsy, however, this isn’t true.

This bacteria does attack your fish, but only when your fish’s immune system is already compromised, whether that be from another illness, poor diet, poor water quality, or stress.

Dropsy is a symptom of the gills and kidneys not functioning properly, so you need to find the cause of this, to know what has caused dropsy in your fish.

Stress factors in an aquarium include:

If none of the above apply then your fish may have a tumor or other disease, in which case you need to contact your vet.

How To Prevent Dropsy

How To Prevent Dropsy

Because dropsy in fish is generally caused by stress, to prevent dropsy you need to provide a stress-free healthy environment for your fish to thrive in.

You can reduce the stress factors in a fish tank by:

  • Testing the water regularly and making sure the parameters are stable and healthy
  • Keeping the water at the correct temperature and avoiding sudden temperature changes
  • Cleaning your fish tank regularly and performing water changes to keep the nitrate at safe levels.
  • Feeding your fish a high-quality varied diet.
  • Not overstocking your tank, as this can crash the nitrogen cycle and lead to aggression amongst tankmates
  • Not overfeeding your fish, as leftover food will rot and release ammonia into the water
  • Always quarantine new additions before adding them to your tank

How To Treat Dropsy In Fish

How to treat dropsy in fish

Sadly, there is no miracle cure for dropsy, as it can be caused by many things, so dropsy fish treatment will vary based on the cause.

If you suspect any of your fish may have the early warning signs of dropsy you can either contact your local fish vet or follow a multi-step treatment plan.

There are no guarantees that any dropsy fish treatment will be successful, but following these steps will give your fish the best possible chance of recovery if you’ve caught it early enough.

Please bear in mind I am not a qualified vet, so it’s always advisable to contact a qualified vet before trying home treatments.

1. Isolate the affected fish in a quarantine/hospital tank.

2. Add Epsom salt to the quarantine tank to aid your fish with osmosis. The salt will help draw out excess water from the fish’s body.

Fully dissolve ⅛ of a teaspoon of Epsom salt per 5 gallons of water. Avoid scented Epsom salts and buy the highest purity that you can.

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3. Feed your fish high-quality food.

4. Dose the quarantine tank water with antibiotics formulated for gram-negative bacteria, such as Seachem Kanaplex or API Melafix.

I’ve used Seachem Kanaplex along with Seachem Focus (Seachem Focus binds medication to fish food to make it easier to treat your fish) for dropsy and other bacterial infections with great results.

They’re 2 of the products I always have in stock, as you never know if any of your fish will suddenly become unwell.

Seachem KanaPlex
Seachem Focus

Optional Treatment

You can also give your fish an Epsom salt bath once per day, this is where you dip the fish in a higher concentration of Epsom salt for a short time.

This process can be stressful for your fish, so it’s up to you whether you try this treatment.

  1. Add some water to a separate container, and make sure you use tank water or tap water treated with a water conditioner. 
  2. Make sure the temperature is the same in your treatment tank and quarantine tank so that it doesn’t cause shock/stress to your fish.
  3. Add 1 level tablespoon (15 grams approx) of Epsom Salts per 1 US gallon of water. 
  4. Dissolve the Epsom salts fully in the treatment tank water.
  5. Add your fish to the treatment tank for 15 minutes (use a timer!).  Keep an eye on your fish as they can get a little stressed out at first and try to jump out of the treatment tank.
  6. Remove the fish from the treatment tank and add it back into the quarantine tank.
  7. Monitor your fish to see if there are any improvements.
  8. Repeat steps 1-6, once per day until you see an improvement.

If there is no sign of improvement in your fish after 10-14 days, then sadly there may be nothing more you can do.

Find A Fish Vet Near Me

If you would like to seek veterinary advice you can find a specialist aquatic vet in your area using the links below:

As you now know, dropsy is one of the most serious things you’ll have to deal with as an aquarist. Once you start to see the more advanced symptoms, chances are it’s already too late to do anything for your fish.

The bottom line is, if you keep stress factors in your aquarium to a minimum, you shouldn’t have to deal with dropsy.

Check out the Aquarium Health section for more guides like this to keep your fish tank in tip-top shape.

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Hey, fellow fish enthusiast 👋! I'm Paul and I've been an aquarium addict since I won my first goldfish at the fair many years ago. Let me share with you the knowledge that I've gained along the way (and avoid the mistakes I've made!), so you too can create an underwater paradise for your aquatic friends.