Why Did My Pregnant Guppy Die? (Before & After Giving Birth)

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Unfortunately, it is pretty common to see a pregnant guppy fish die. I’ve experienced this issue myself several times in the past. As time passed, I learned that several factors were causing this problem. Luckily, there are ways to prevent this from reoccurring in the future. 

Pregnant guppies usually die because of a complication at birth, with the most common being a fry stuck in the birth canal. However, some guppies die before or after giving birth due to stress factors, including aggressive tankmates, inadequate water parameters, and toxins.

As we move forward, I will elaborate on what may cause your guppy to die before, after, and during pregnancy. Then, I will list several tips to ensure that it doesn’t happen again.

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 Did My Pregnant Guppy Die?

Guppies are almost always pregnant. If you have both genders in the aquarium, they will add between 5 to 80 babies to the water every thirty days, but only if they survive the pregnancy. This is not a guarantee.

Pregnant guppies die all the time. Some of them die before they give birth. Others die after giving birth. The factors that lead to death in both cases are almost always the same, including:

1. There Were Labor Complications

A guppy can die from labor-related complications. The most common of these complications are scenarios where a fry gets stuck in the mother’s birth canal. This can happen because of deformities.[1]

Some people respond by pulling the fry out with tweezers. But even with the stable hand of a vet, the mother and her baby are unlikely to survive.

Some guppies die quickly during these situations. For others, death is slow and painful. You can try raising the temperature by a few degrees. But this practice cannot guarantee positive results.

2. Your Guppy Was Stressed

Healthy guppies can die because of stress. Pregnant guppies are even more vulnerable to this ailment because pregnancies are already stressful.

They strain the physical health of female fish, which is why these creatures become so lethargic and inactive as the pregnancy advances. You can worsen their situation by exposing them to aggressive tankmates, dirty water, and toxins.

Stress is a difficult ailment to identify. On the one hand, it attracts noticeable symptoms, including loss of appetite, discoloration, labored breathing, and listlessness.[2] On the other hand, those symptoms are also associated with livebearer pregnancies.

A pregnant guppy will stop eating. It will also become timid and discolored over time. Therefore, it is not easy to differentiate between stress and ordinary signs of pregnancy.

Stress can affect guppies even after they give birth. If you are new to livebearers, experts will encourage you to place the females in a separate tank once they give birth. You have to give them a day or two to recover before reintroducing them to the main tank.

This shows you the amount of exhaustion they have to contend with after giving birth. If they encounter stressful stimuli shortly after giving birth, they are more likely to die.

Examples of stressful stimuli include massive water changes, aggressive males trying to mate with them, and fluctuating temperatures.

3. You Used A Breeding Box Too Early

Do you have a breeding box? These devices are convenient because they sit inside the main tank. You don’t have to buy a new tank to accommodate pregnant fish. You can hide the guppies in the breeding box until they give birth.

Once the female pushes out the fry, you should remove it from the breeding box. The box protects the fry from any fish that wants to eat them. You can keep the babies in the box until they are large enough to survive in the main tank.

Breeding boxes are a sensible solution. Unfortunately, they also expose livebearers to dangerous stress levels.[3] They will induce premature labor in pregnant guppies. Additionally, you are more likely to encounter labor complications, some of which may lead to death.

A female forced to remain in the box after giving birth could also die from the stress. You can increase the guppy’s chances of surviving by placing it in the box shortly before it gives birth and then pulling it out of the box the moment the birthing process ends.

4. The Water Parameters Were Wrong

It is not enough to prepare a separate tank for pregnant guppies. You must furnish the aquarium with the correct parameters. That includes a pH of 6.9 – 7.5, hardness of 9 to 10dGH, and a temperature of 75 – 80 degrees F. Warm water is better because it expedites the gestation period.

Also, ammonia, nitrates, and nitrites should be kept at 0 ppm. To measure these, I personally use the API Water Test Kit (link to Amazon). It is a bit more expensive than other kits. However, it is highly accurate and lasts for eight hundred measures.

The female guppies will suffer if you permit the parameters to slide out of the appropriate range. The wrong parameters can compromise the health of ordinary non-pregnant guppies, especially if they persist.

Since pregnant fish are vulnerable, they are more likely to die. Some guppies will die before their due date. Others will give birth and then die because of the combined stress of labor and the wrong parameters.

5. You Moved Your Guppy To Another Tank

Have you ever added a new fish to your aquarium? If you forgot to acclimate it, the creature probably struggled with the shock of the transition for several days.

Even if you acclimated the fish, more than likely, it took a while for the guppy to grow accustomed to the aquarium. The best way to protect pregnant guppies is to place them in separate tanks where the females can give birth in peace.

But if introducing a new fish to your community tank can induce shock, moving pregnant fish to a separate tank may produce worse results because the expectant mother is sensitive.

Some guppies will abort their offspring. Others tend to extend their gestation period. You also have those that die. Whether they die before or after giving birth depends on the conditions in the new tank and the health of the pregnant guppy.

6. Your Pregnant Guppy Was Sick

Many aquarists blame every symptom they observe in pregnant guppies on the pregnancy. They don’t realize that diseases and infections can produce the same symptoms you see in pregnant fish. That included lethargy, inactivity, loss of appetite, and labored breathing.

Pregnant fish have weakened immune systems.[4] Therefore, they are less likely to survive diseases and infections. It shouldn’t surprise you if they die during labor.

A helpful indicator would be checking the other fish in your tank. If your pregnant guppy wasn’t the only fish that died, there was probably an outbreak in your tank. Also, sick guppies present additional symptoms, including white spots, ripped fins, sores, and heavy breathing.

7. Old Age And Genetic Issues

Guppies have a lifespan of three to five years.[5] Old guppies can still give birth – though some studies have shown that guppies can experience menopause.[6]

Older guppies are less likely to survive their pregnancies because their bodies cannot withstand the strain of the birthing process.

You cannot blame the death of every pregnant guppy on your inability to create a conducive environment in the tank. Some guppies have bad genes.

The females keep producing deformed fry that block the anal vent during labor because of a genetic anomaly in your guppy population. Most people respond to genetic anomalies by euthanizing their stock of guppies and starting over.

What Should I Do If My Pregnant Guppy Died?

If your pregnant guppy died, start by checking the water parameters. As was mentioned earlier, stress is usually the cause of death, and inappropriate water conditions will stress your pregnant guppy even more.

These are the ideal water parameters for pregnant guppies:

  • Temperature: 75–80° F (24-27° C)
  • Water pH: 6.9–7.5
  • Hardness: 9-10 dGH
  • Ammonia and nitrites: 0 ppm
  • Nitrates: <20 ppm

If the water parameters are correct, the next step would be providing the next pregnant guppy with a stress-free environment. You can easily do that by removing aggressive tankmates, including the male guppies themselves.

It is best to put other fish in a separate tank while leaving the pregnant guppy in the original one. Then, add a few plants so that the female can hide and give birth in peace. Artificial plants are great because they don’t alter the water chemistry.

Ultimately, consider an aquarium divider instead of a breeding box if you’re afraid that the pregnant guppy will eat the fry. A divider will allow the fry to swim to the other side of the tank while leaving the mother far away.

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.


There are many reasons why pregnant guppy fish die. Some of them are out of your control. For example, old and genetically deformed guppies probably won’t survive giving birth. But those cases are individual, and you shouldn’t see the phenomenon repeating itself.

If it’s not the first pregnant guppy that dies in your aquarium, you should test the water parameters and ensure a stress-free environment. I also suggest avoiding breeding boxes, as they induce stress and require calculated timing.


  1. https://urbanfishkeeping.com/do-guppies-die-after-giving-birth/
  2. https://aquariumfishmag.com/5-reasons-pregnant-guppy-died/
  3. https://guppyexpert.com/guppy-fish-died-after-giving-birth/
  4. https://www.bettacarefishguide.com/do-guppies-die-after-giving-birth/
  5. https://www.fishlore.com/Profiles-Guppy.htm
  6. https://www.nbcnews.com/id/wbna10643970