Why Is My Pregnant Guppy Not Giving Birth?

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Raising a pregnant guppy can be stressful. I remember how confused I was when I saw my guppy getting larger and larger; however, it didn’t give birth. There was a point when I actually thought that the fish would abort the fry. Fortunately, as years passed, I gained some experience in this field.

Pregnant guppies may refuse to give birth for the following reasons:

  1. They aren’t being fed properly.
  2. The water temperature is too cold.
  3. The guppy is still in the early stages of pregnancy.
  4. The pregnant guppy is stressed.
  5. There are bullying tankmates in the aquarium.
  6. The pregnant guppy is sick.

As we move forward, I will elaborate on why pregnant guppies may refuse to give birth. I will also include a helpful video that will help you determine if your fish is pregnant. Sometimes, guppies may seem pregnant, but they are actually sick.

Still curious? Feel free to check my complete guide on pregnant guppy fish. There, I discussed how to care for pregnant guppies, how long they remain pregnant, how to identify signs of pregnancy, and a lot more.

Why Is My Pregnant Guppy Not Giving Birth?

Guppies are sexually mature at five months. They can start breeding at this stage. First, the male has to inseminate the female. Once the male fertilizes the eggs in the female’s body, they will hatch into fry that the pregnant guppy can push out of its anal vent four or five weeks later.

But what happens when a female guppy refuses to give birth? What would cause such delays? You have several factors to consider, including:

1. There Isn’t Enough Food In Your Tank

Does your aquarium have food? Research has found that guppies can extend their gestation period to improve their offspring’s chances of surviving in environments where food is scarce.[1] 

The studies that explored this issue found that guppies in regions with fewer predators were more likely to produce larger babies, but in smaller numbers, because the guppy population had ballooned. 

Large numbers of guppies had to fight for the limited supply of algae and diatoms. As such, some guppies would gestate their young ones for more extended periods, allowing them to attain higher levels of maturity before they pushed the creatures out into the world. 

If the food in your aquarium is scarce, the pregnant guppies may respond by extending the gestation period. As a rule of thumb, feed your pregnant guppy three to five small meals each day.[2]

2. The Water Is Too Cold

You can expedite a pregnant guppy’s gestation period by increasing the temperature, but you can’t do this suddenly.[3] You should raise the temperature by a degree or two each day. The optimal temperature is 82 degrees F.

This way, you can reduce the gestation period by several days, possibly even a week or more. However, doing the opposite will delay the pregnancy. 

At 82 degrees F, not only will the guppies grow at a faster rate, but they will produce more offspring.[4] 

On the other hand, permitting the temperature to fall to 72 degrees F will reduce the guppy’s growth rate. This temperature will extend the creature’s gestation period while decreasing the number of babies it produces. 

As was already noted above, food scarcity will make things worse. It will encourage the guppies to gestate their babies for more extended periods. 

3. It’s Too Soon For Your Guppy To Give Birth

Guppies are typically pregnant for 21 to 31 days. On occasion, they can give birth within 21 days, depending on the conditions in the aquarium. But for the most part, aquarists expect guppies to give birth within 30 days.

The gestation period starts once conception occurs; that is to say, you start counting from the moment the male fish fertilizes the female’s eggs. 

If your guppy has seemingly refused to give birth, you should consider the possibility that conception occurred later than you estimated. Your calculations are probably off by one or two weeks. 

Also, bear in mind that female guppies can store sperm. This allows them to conceive at any moment without the direct involvement of a male guppy. Therefore, it becomes challenging to determine the exact moment that conception occurred. 

Pay attention to the signs. If you think the guppy is overdue, but it isn’t quite as large as a guppy that is going to give birth, you should consider the possibility that you miscalculated.

4. Your Pregnant Guppy Is Stressed

Stress can be dangerous. Various factors can cause stress in pregnant guppies, including the wrong parameters, fluctuating conditions, food scarcity, violent tankmates, etc.

People think that stress will simply delay a guppy’s pregnancy. But that is the least of your worries. Stressed fish will probably abort their pregnancies.

They may also absorb the fry as nutrients. In other words, you will wait for the guppy to give birth in vain. The signs of pregnancy will slowly dissipate. 

5. There Are Bullies In Your Tank 

Did you separate your pregnant guppy? Guppies are bad parents. You cannot rely on the fish to raise their young ones because the guppies will eventually eat their babies. You have to keep the guppies in a separate tank until they give birth.

Once the mother drops the fry, move it back to the main tank. If you kept the pregnant guppy in the community tank, it could have given birth without your knowledge. In other words, the mother or the other adult fish ate all the fry before you noticed them.

Many aquarists use breeding boxes to protect the mothers and their offspring from predators. But breeding boxes cause stress. And as you now know, stress can compel guppies to abort or absorb their babies.

This is why aquarists wait until their guppies are on the verge of giving birth before placing the fish in breeding boxes. Once the mothers give birth, they remove them immediately. They don’t want the fish to spend more time than necessary in the breeding boxes. 

6. Your Guppy Is Sick

Pregnancies are a significant source of stress. This is why pregnant guppies are so lethargic and inactive. It is also why some guppies die before or after giving birth.

If your guppy is sick or old, it will either extend the gestation period or abort the babies. Sick and old guppies are also more likely to die before or after giving birth. 

It can be challenging to diagnose a sick guppy fish that is also pregnant, as some signs of pregnancy are also the signs of sickness. That includes a loss of appetite, a tendency to hide, a swollen belly, and erratic swimming.

However, sick guppies may look different. You may notice ripped fins, bleeding gills, dull coloring, wounds, open sores, and white dots.[5] Sometimes, sick guppies tend to swim at the bottom of the tank.

If you notice these signs, I highly suggest consulting an aquatic veterinarian. An expert may help you choose the proper remedy and perhaps save your sick guppy.

7. Your Guppy Isn’t Actually Pregnant

Is your guppy pregnant? Most aquarists know that a pregnant guppy will expand in size as its eggs hatch and the fry develop. But some newcomers do not realize that a guppy’s belly can swell for other reasons. For instance, guppies can contract dropsy.

Dropsy will cause a guppy’s belly to swell with fluids. The illness is difficult to treat, if not impossible, because it harms the organs. If your fish is swollen, look for skin lesions and pinecone scales.[6]

If you’ve ruled out dropsy, look for signs of constipation or overeating. Better yet, look for definitive symptoms of pregnancy. Bloating is not enough. A pregnant guppy’s gravid spot will grow darker and more prominent:

Besides losing its appetite, the fish will either lash out aggressively or hide, depending on its temperament and the attitudes of the guppy’s neighbors. You can also look for a distended anal vet and the eyes of the fry in the fish’s belly.

If the guppy’s bloating isn’t accompanied by these symptoms, you might have misdiagnosed the fish. It is not actually pregnant. You may ask a vet to identify the factors responsible for the bloating before the fish suffers lasting harm.

If you still feel unsure about this topic, here is an excellent Youtube video that will help you identify a pregnant guppy fish:

If you found this article helpful, these may also interest you:

Pro tip: If your guppy is pregnant and will give birth soon, you’ll need to know a little more about the babies. On that matter, feel free to check my complete guide on guppy fry.


If your guppy isn’t giving birth, first ensure that the fish is indeed pregnant. There are many signs of pregnancy, including a darkening gravid spot, loss of appetite, aggressive behavior, and a belly that is consistently getting larger.

In some cases, it is still too early for the fish to give birth. Guppies are typically pregnant for 21 to 31 days. It is possible that you haven’t waited long enough or started counting too early. You should also consider environmental factors, such as temperature, tankmates, and food.

For example, a too cold tank may extend the gestation period. That is typical for temperatures lower than 72 degrees F. Ideally; you should aim for 82 degrees F. I also suggest feeding your guppies three to five times a day.


  1. https://www.futurity.org/guppies-predators-gestation-evolution-1571282/
  2. https://small-pets.lovetoknow.com/pregnant-guppy-fish
  3. https://guppyexpert.com/guppy-fish-gestation-period/
  4. https://www.aquariumcoop.com/blogs/aquarium/guppy-care-guide
  5. https://kingsoftheaquarium.com/20-signs-that-your-guppy-is-sick/
  6. https://www.thesprucepets.com/dropsy-in-aquarium-fish-1381806