Your Guide To Symptoms & Treatment

Keeping your aquarium healthy is the number one priority of you being an aquarist. So, if a fish develops dropsy, that’s a problem you need to deal with.

But many fish farmers don’t know where to start when it comes to dropsy. The causes, symptoms and treatment are all a mystery!

That’s why we created this resource. It will teach you everything you need to know about dropsy in fish and how you can get it out of your aquarium.

Let’s start.

What is dropsy?

Before going into details, we should start with a quick explanation of what dropsy is.

To put it simply, dropsy is a condition that presents as swelling or bloating in fish. It can affect the vast majority of species (including bettas and all types of goldfish) that are kept in aquariums and has a number of different possible causes.

This swelling is usually isolated from the abdomen (belly) of the fish it affects. It can become quite pronounced depending on the severity.

While some owners mistake it for a cosmetic issue, it’s much more serious than that. Dropsy is often fatal.

Author’s note: It should be emphasized that dropsy is a condition and not technically a disease. This is a common mistake that has led to a fair amount of misinformation over the years.

Is dropsy contagious?

For the most part, dropsy is usually not contagious. However, you’ll assume this is for the sake of caution when providing treatment (more on that later).


There are a number of common and obvious dropsy symptoms to look out for. However, there is one that stands out the most:


A fish that is seriously affected by this condition will exhibit swelling primarily in its abdomen (although this is not always the case). This is caused by a buildup of fluid in the tissues.

A goldfish with dropsy

If things have gotten to the point where there is significant swelling in their belly, the outlook is not good. This means that things have progressed to the point where it affects their whole body (namely their organs).

Luckily, there are other symptoms you can watch out for that usually occur before things get that bad. Your fish could develop dropsy if they have:

  • Eyes that start to bulge and swell
  • Scales that begin to point outward instead of flush with their body
  • A loss of color in their gills
  • Aileron tightening
  • A curve developing in their spine
  • Pale droppings
  • Swelling near their anus
  • A loss of appetite
  • A lack of energy and movement

If you regularly observe your fish, one of these symptoms should really stand out. Once you see something that concerns you, it’s best to take action immediately before the condition progresses further.


There are many causes of dropsy that you should know about. Although we’ll get into specific treatments and prevention a bit later, understanding the causes of this condition will also help.

Scientifically, the root cause of the actual symptoms is a type of bacteria called Aeromonas. Contrary to what some people think, this bacterium is present in your tank at all times. It is not a foreign invader that comes and wreaks havoc in your aquarium.

It is only when a fish has a weakened immune system that the bacteria becomes a problem.

This means that you should not consider the bacterium as the cause of the dropsy. The real cause is what compromised your fish’s immune system in the first place.

Here are the usual culprits:

  • Bad water quality
  • Inconsistent water temperature
  • Fluctuations in nitrites and ammonia
  • A poor diet

The good thing about all of these is that they are completely under your control. If you are able to maintain a healthy and optimal habitat for your fish, these problems are unlikely to occur.

Treatment of dropsy

We know that many aquarists want to learn how to cure dropsy. Unfortunately, this is not possible. There is no quick and easy remedy that will magically make this condition go away.

Instead, you will need to go through a multi-step processing process. Results will vary depending on the severity of the dropsy case, but you will be giving your fish the best possible chance.

Quick Quarantine

The first and most important thing you can do when trying to treat dropsy is to quarantine the affected fish. This means a completely separate tank that has the necessary water parameters for any species you suspect may be sick.

It is best to keep this tank bare and devoid of decorations. Even though your fish normally prefers plants, rocks, and driftwood, you won’t want to add variables to your aquarium. Just a filter and a heater will do.

Once you have the quarantine tank ready to go, move the affected fish.

Author’s note: Although dropsy is not normally contagious, removing the diseased fish allows you to provide better direct treatment without affecting others.

Add salt

Now that the affected fish has been isolated, it’s time to add some salt to the tank. The general rule to follow is 1 teaspoon for every gallon of water in the tank.

Salt is helpful in treating dropsy because it can extract some of the water and fluids accumulated in their body. This will help make your fish more comfortable and put them in a better position to recover (uncontrolled swelling is always fatal).

There are a bunch of different salt products you can use, but we only recommend one brand. Even if you don’t have any dropsy fish right now, we think it’s a good idea to have some on hand just in case:


API Aquarium Salt for Health and Disease Recovery

API Aquarium Salt for Health and Disease Recovery

  • Promotes healthy fish and recovery from disease through increased electrolytes
  • Improves fish respiration in freshwater aquariums
  • Effective solution to treat dropsy
  • Made from evaporated seawater for all-natural results

Step up their diet

Although you should always strive to provide the perfect diet, it is absolutely necessary when treating dropsy.

Here’s an example we like:

Imagine if you were trying to fight off a serious illness by eating only cereal at every meal. You don’t need to be a nutritionist to know that it won’t end well!

High-quality food will not only provide essential nutrients and vitamins to aid the healing process, but it will also help your fish boost their immune system.

The perfect diet will obviously vary depending on the species you are dealing with. We recommend that you read an in depth guide to caring for your fish if you are unsure of what foods to prepare.

Use antibiotics

The last option for the treatment of dropsy is a trusted antibacterial drug. Depending on the level of severity and how your fish reacts to other treatment methods, you may not need to go this route.

However, if their symptoms do not improve, antibiotics are the next step.

It is very easy to apply the medicine to your reservoir. All you have to do is follow the instructions of the product you buy.

But choosing the right product is very important. There are many on the market and they all claim to offer the same benefits.

Fortunately, we can recommend the best. The antibiotic below has been used by countless aquarists to help treat dropsy and other conditions. We personally know many satisfied users.

There are obviously no guarantees when it comes to medication (as you know there is no cure for dropsy), but this antibiotic will give you the best chance.


API MELAFIX Medication

API MELAFIX Medication

  • Heals bacterial infections, treats dropsy and repairs damaged fins and open wounds
  • Contains natural and botanical tea tree extract to help fish quickly and quickly
  • Also helps treat newly introduced fish to reduce the risk of disease outbreaks in freshwater aquariums
  • Use daily for a week when treating infections and for 3 days as a preventative when adding new fish

How to prevent it

If you read the section of this guide on the causes of dropsy, you can probably guess which methods are most effective in preventing it.

Maintaining good water quality and a healthy tank will greatly reduce the likelihood of your fish developing dropsy. Almost all of the factors that cause this condition stem from suboptimal living conditions.

First, take water quality very seriously. You need to maintain consistency with baseline water parameters and ensure nitrite and ammonia levels are stable.

You should always strive for clean, healthy water by using proper filtration, performing water changes, and not adding unnecessary organic waste due to overfeeding.

Author’s note: In order to keep an eye on these levels, you should regularly test your aquarium water to make sure nothing goes unnoticed. You can prevent many problems simply by being informed and reacting quickly.

Second, don’t be lazy with their diet. A healthy, balanced diet will make your fish healthier and more resistant to disease.

Go the extra mile to provide some variety and try to feed your fish the highest quality food you can find. Spending a little more time now will save headaches and pain later.

Finally, do everything you can to minimize stress in the tank. Fish that live in a constant state of stress are at a much higher risk of developing diseases and illnesses. Keep your fish in a stable tank that meets their needs and they will be very happy.


Treating dropsy is something that no aquarist wants to treat. But unfortunately, that’s part of the hobby.

That’s why it’s a good idea to educate yourself about this condition and the options available to you. By knowing more, you will be prepared if one of your fish is unlucky enough to catch it.

The good thing is that by simply remaining committed to maintaining an optimal habitat, it will probably never happen! Go the extra mile for your fish and they will live long and healthy lives.

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