Dropsy in Fish – Causes, Symptoms & Treatment

Dropsy in guppy Fish

Dropsy is a common condition that affects many different species of fish in captivity. 

It is important that you are aware of this issue so that you can recognize the signs. Since it can become quite serious, this information is absolutely vital.

What is Dropsy?

Dropsy is essentially a condition that causes a fish’s abdomen to swell up due to a buildup of water in their stomach. It isn’t so much a disease as it is a health problem that can get serious very quickly.

Causes of Dropsy

1. Bacterial Infection

A bacterial infection is at the root of this condition. The infection causes massive swelling of the abdomen. The bacteria are already in the water, but fish can become particularly vulnerable to it if they are stressed. This stress can be due to overcrowding or some other issue. 

2. Unclean Water

Sometimes it is just a matter of unclean water. This is why it is so important that you change the water in your aquarium on a regular basis. Bacteria can accumulate very rapidly, which puts the health of your fish in danger.

3. Inadequate Diet

It is also possible for a fish to contract Dropsy if they are being fed an inadequate diet on a daily basis. Lack of certain crucial nutrients can leave your fish weakened and vulnerable to the bacteria that causes this condition.

4. Changes in nitrate levels

A change in nitrate or even ammonia levels in a fish’s tank can quickly lead to Dropsy as well. Inadequate oxygen inside the tank can be a big problem for many reasons. This is why you should typically put in at least a couple of plants.

5. Old age

Fish can also develop this health issue because they are old and therefore have a weakened immune system. If your fish is at the end of its life, this is certainly a possibility.

Dropsy in betta Fish e1580927893116

Dropsy Symptoms

It is important that you are aware of the symptoms of Dropsy so that you can quickly identify this problem with your fish. The sooner you recognize it, the better your pet’s chances will be of surviving.

Some of the most common symptoms of this condition include:

  • Bulging eyes: You’ll notice that your fish’s eyes seem to bulge right out of their head in a highly unusual way.
  • Paleness: If your fish’s gills seem paler than usual, it is probably because they are sick with this type of bacteria.
  • Swollen anus: Sometimes the anal gland of a fish will swell as well. This can be a harder symptom to identify unless you actually handle the fish.
  • Sluggish behavior: Lethargy is another common sign of Dropsy that you’ll want to look out for.

Dropsy Treatment

There are a number of things you can try when it comes to treating Dropsy, but some methods tend to work better than others. Some people will tell you that it is best to euthanize all affected fish so that the bacterial infection doesn’t spread.

The first thing you’ll want to do is to transfer all the infected fish in your tank to a separate one. You are essentially quarantining these fish to prevent the spread of the infection.

Next, you will need to put in just a teaspoon of salt for every gallon of water in your isolation tank. Continue to feed the fish that you have quarantined a healthy and nutritious diet. You’ll also want to put antibiotics in the fish’s food each time you feed them on a daily basis.

It is important that you continue testing the water in the isolation tank so that you know all the levels are normal. Change the water in the tank where the healthy fish are before putting the fish from the isolated tank back with them.

While there is no guarantee that this method will work every single time for fish with this type of infection, it is worth trying.

Preventing Dropsy

You will have numerous effective ways to keep your fish from getting dropsy, including:

1. Keep Stress to a Minimum

There are certain things that you can do to reduce the amount of stress your fish experiences in their tank. This includes giving them plenty of room to swim around and not putting too many fish in one habitat. Overcrowding is a very common reason for stress in fish, which can weaken their immune system.

2. Feed Your Fish a Nutritious Diet

It’s also important that you know which foods to give your fish each day. Not all of these aquatic animals have the same dietary needs, so you’ll want to keep that in mind. The last thing you want is to buy cheap and unhealthy food for your fish just so you can save a few bucks. You also don’t want to give your fish too much to eat at once, as this can also be problematic.

3. Change Out the Water Regularly

Make sure that you change out the water in your fish tank as often as needed. It is also highly recommended that you regularly check nitrate, ammonia and acidity levels regularly as well. This will ensure that your fish are living in a healthy overall environment.


  • Dropsy is a common health problem that lots of fish develop in captivity, but it can be quite serious.
  • This condition is caused by a bacterial infection.
  • Stress due to overcrowding in a fish tank is a common reason for this condition.
  • Unclean water can also cause dropsy in fish.
  • Some of the symptoms of dropsy include lethargy, bulging eyes, pale gills, and a swollen anal gland.
  • If you want to treat your fish with dropsy, separate the infected ones by putting them in their own tank.
  • Administer antibiotics to these fish in their food every time you feed them.
  • A big part of preventing this condition involves keeping your fish on a nutritious diet while reducing stress.
  • You’ll also want to change the water in your fish’s tank on a regular basis to prevent bacteria from forming.
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