Why Is My Guppy Fish Swollen? (Reasons+Prevention)

A swollen abdomen in guppy fish is something that we should take seriously. It is essential to know the reason behind it as soon as possible so that we can treat it if possible. So, Why is my guppy fish swollen? Let us find out.

There are various reasons behind swollen guppy fish like female guppy is pregnant. Constipation can be the reason behind an enlarged abdomen. If none of these, dropsy is the reason behind an enlarged abdomen. Avoid overfeeding and provide good water conditions to prevent constipation and dropsy.

We will discuss how to know if a guppy is pregnant and how we can treat dropsy and constipation in this article. So, let us get into it.

My guppy fish is swollen.

There can be various reasons behind your guppy fish having a swollen abdomen:

  1. Your guppy fish is pregnant.
  2. Your guppy fish is suffering from constipation.
  3. Guppy fish is suffering from dropsy. 

It is also possible that your female guppy is pregnant, which is the reason behind the enlarged abdomen.

If you keep female and male guppies together in the same tank, then they will breed out of control.

A female guppy will have a big round belly when it is pregnant.

Constipation can also lead to a swollen abdomen.

Overfeeding your guppies can lead to constipation resulting in a swollen abdomen.

Dropsy is a critical condition that is not curable if the bacterial infection is the reason for the drop.

A bacterial infection affects the kidney, resulting in retaining the water, which causes swollen abdomen.

Pregnant female guppy

Pregnant female fish can also be the reason behind the enlarged abdomen.

You must know that guppies are life bearers and give birth to fry.

Guppies are also known as million fish because they can get pregnant right after giving birth to fry.

If we keep male and female guppies in the same tank, then they will breed out of control.

We should keep male and female guppies in the ratio of 1:3, which means one male guppy for every three female guppies.

Now, let us discuss how we can know that our guppy fish is pregnant.

How to know if my guppy is pregnant?

When having male guppies and female guppies in the same tank, the possibility of the reason behind the enlarged abdomen becomes the female guppy is pregnant rather than any other illness.

You can detect if your guppy is pregnant by looking at the gravid spot.

A gravid spot is a dark spot located just behind the anal fin of female guppy fish.

If your female guppy fish is pregnant, the gravid spot will be enlarged and darker.

Pregnant guppy fish will have a big rounded belly.

You will notice some behavior changes in your pregnant guppy fish.

Your pregnant guppy fish will show hiding behavior and aggressive behavior to hide its weakness.

Other signs are losing appetite and staying still at one corner of the aquarium.

When your pregnant fish show hiding behavior by separating itself and hiding behind plants or corners of the aquarium, it’s an indication that it is about to release the fry.

At this moment, you have to separate the pregnant guppy fish and move it to another tank or a breeding box.

It is essential to save the fry.

As soon as guppy releases the fry, other tankmates will try to hunt it down as they take the fry as their food.

When the mother guppy releases the fry, you have to separate the mother guppy from the fry.

Guppies don’t have parental instincts and will feed on their fry.

Make sure to have the same water temperature of another tank as it is in the guppies tank when placing the pregnant guppy in another tank.

If you are placing your pregnant guppy in a breeding box, then make sure not to keep your guppy there for a long time.

It can cause stress to them, which will result in miscarriage.

Also, don’t keep the fry for more than two weeks in a breeding box, as it can stop their growth, and they can also form deformities.

Also read: Is My Guppy Pregnant?

How often can a female guppy get pregnant?

Female guppies can get pregnant right after giving birth.

The gestation period of pregnant female guppies is 25-30 days.

This means that female guppies can get pregnant every 30 days.

Sometimes, separating female guppy from the mix-gender aquarium after releasing the fry wont help.

Because female guppies can get pregnant multiple times from single fertilization.

Guppies can release up to a hundred fry at a time.

Guppies can make your aquarium overcrowded very quickly.

For preventing the problem of overcrowding, you can do these things:

  1. Separate male and female guppies.
  2. Introduce female betta fish in your guppies aquarium.
  3. Remove hiding places from your guppies aquarium so that tankmates can easily hunt down the fry.
  4. Keep only male guppy fish.


Another reason behind your guppy swollen abdomen can be constipation.

Constipation and indigestion can swell the belly.

Constipation can make your guppy fish come into critical condition.

Guppy fish will be less active and will refuse to eat anything.

The primary cause of constipation is overfeeding.

Overfeeding can cause indigestion and swollen belly.

Feeding your guppy fish food that can extend inside their belly like deep-frozen foods can cause constipation and swollen abdomen.

However, making your guppy not to eat anything for a couple of days will and then offering cooked peas in small amounts will eventually solve this problem.

Constipation issues usually get solved in two to three days.

If the swollen abdomen issue doesn’t get solved in 2-3 days, it is not constipation, and dropsy is now the explainable issue here.


Dropsy is not a disease but a physical presentation that shows kidney failure.

Guppy fish will retain the water, resulting in a round belly with scales sticking out.

It is a very critical condition.

Dropsy has various reasons, such as poor water conditions or bacterial infection.

Such infections can directly attack the kidney, resulting in the retaining of water.

The possibility of surviving once dropsy affected the fish is low.

How to cure dropsy?

It is pretty hard to cure fish suffering from dropsy.

The problem is irreversible once the signs start to occur, and the reason behind the dropsy is a bacterial infection.

Isolate the sick guppy in another tank, and if you find any infection issue behind dropsy, then there is no cure.

The only option left here is to euthanize your guppy fish by applying the clove oil or stun and stab method.

Euthanizing sick guppy is essential to ensure that the infection is not being spread to other tankmates.

In case the infection is not the reason behind dropsy, then you follow this process to cure your guppy:

  1. Place your guppy fish in a hospital tank.
  2. Add one tablespoon of Epsom salt per one gallon of water.
  3. Feed your guppy fish good quality nutritional food.
  4. Provide antibiotics to your sick guppy through water or food.
  5. Make sure to keep a regular check on water temperature and condition every day.

Perform regular water changes and provide your guppy with adequate and stable water parameters to prevent dropsy.


There can be various reasons behind guppy fish being swollen. However, the pregnant female guppy is the primary reason why male guppy and female guppy live together in the same tank. Constipation and dropsy are other reasons.

Maintain the water condition and provide adequate and stable water parameters to prevent dropsy.

Avoid overfeeding your guppy fish. Instead, feed them in a quantity that they can finish in 1-2 minutes.

Reference: ResearchGate, Wikipedia,

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