Why Pregnant Guppy Died Before Giving Birth?

Guppies breed a lot, allowing guppy keepers to even start a breeding business for profit. The gestation period is between 21 and 28 days, after which the female can get pregnant almost immediately.

Not to mention, guppy females keep the male’s sperm inside them for up to 10 months or more. They will use the sperm to self-impregnate every month when no male is around them to take over the task.

A female will generally deliver anywhere between 20 to 200 fry, with the average standing at around 50. Multiply this by the number of pregnant females and consider their breeding proficiency, and you can see why guppies are so popular.

If you aim to set up multiple fish tanks, you need a small guppy population of 8-10 specimens. Fast forward 3 months, and you will already have another tank or two filled with newer generations of guppies.

However, it’s not all fun and games when discussing guppy breeding. Things may not always go as intended. Adult guppies may attack and eat the fry, or the female itself can die before giving birth.

Today’s article will discuss the latter, looking to dive into the factors that could cause such an event.

Experiencing Stress During Pregnancy

Guppy stress is a common occurrence, especially when the living conditions are not ideal. Stressed guppies may display behavioral changes like erratic swimming, swimming near the substrate, low appetite, hiding behavior, etc.

If you don’t remove the cause of stress, the guppy’s immune system will drop, leaving the fish vulnerable to infections, parasites, and illness. Extended stress can even lead to death, which is why it’s essential to identify the causes fast and remove them.

Some of the factors leading to guppy stress include:

  • Predatorial tank matesGuppies are peaceful and relatively small fish that can turn them into prey fast. If your guppies have aggressive tank mates that bully them, they will become stressed. You will soon see them constantly looking for hiding or displaying lower levels of energy than normal. Not to mention, bullying can take a turn for the worse if the other fish actively attack your guppies. They might hurt and even kill them in the process.
  • Pushy malesGuppy males can become extremely pushy and persistent during the mating phase. They will compete for the females and follow them around the tank even after they’ve mated. That’s because guppy females often mate with several males, which will drastically increase male competition. The situation grows even worse when you have more than 1 guppy male per 3 females. The goal is to detect signs of female stress due to persistent male behavior and remove the former from the tank. You can place it in a separate environment when the female approaches labor so that it can give birth with minimal distractions.
  • Illness – Many fish illnesses will first cause behavioral changes before triggering any physical symptoms. One of them is stress-induced behavior consisting of lower appetite, anti-social behavior, low energy, erratic swimming, etc. If you notice similar signs, I advise investigating the reasons immediately. If your female guppy shows signs of illness, quarantine it and provide adequate treatment to address the disorder in its incipient phases.

Improper Water Conditions

All guppies will suffer due to improper water conditions, pregnant females especially. Water quality can drop due to a variety of reasons, including:

  • Overfeeding and overcrowdingOverfeeding will lead to a lot of unconsumed food, while overcrowding will increase fish waste in the water. Not cleaning the tank properly will lead to spikes in ammonia levels which can prove fatal for guppies.
  • Fluctuating temperatures – As tropical fish, guppies prefer steady and warm waters with stable temperatures. The ideal temperature range for a guppy population is between 72 and 80 F approximately. You should make sure that it doesn’t drop or climb above these general parameters too much. If the water temperature fluctuates too much or too often, the guppy’s immune system will drop, leaving it vulnerable to illness and parasites. In this sense, I suggest monitoring the water temperature constantly to ensure it remains within the acceptable values.
  • Improper filtering – A filter malfunction or a weak filtering system will both have the same effect – a decrease in water quality. Harmful bacteria may multiply, affecting the fish and the aquatic flora, the water oxygenation will drop, and your guppies may fall ill. A faulty or improper filtering system can quickly decimate your guppy population if you’re not paying attention.

Similar problems may occur when moving the pregnant female into a different tank, which I strongly advise if you want to protect the fry. The breeding tank should provide the female with similar water conditions to reduce the shock coming from changing environments.

I have seen situations where the fluctuations in water parameters between the two tanks have killed the pregnant female soon after relocations. Yes, the situation is that volatile.

Preexistent Illness

The female guppy may also die due to preexistent illness that arose before the pregnancy. This is where prevention can save your guppy’s life before the condition aggravates any further.

There are tale-telling signs to consider in the initial phases of any disease. These include changes in eating patterns, erratic behavior, abnormal swimming, etc.

Some of the conditions that your guppy may contract are deadly, others can be treated. It’s also important to note that fish diseases like TB are contagious and will quickly infect the rest of the population. In this context, taking preventive measures and identifying the conditions before they worsen is key to saving your guppies’ life.

First, you must ensure quarantine. Remove the ill fish and place it in a separate tank where you can administer proper treatment. If the treatment fails, at least you know you’ve done everything you could.

Pregnancy Complications

Sometimes, there’s nothing you can do to save your guppy’s life. The female may face pregnancy complications that may lead to its death soon into the labor. A preexistent condition may cause the fry to remain stuck into the birth canal.

These are unfortunate events that no one can foresee. The good thing is that they are rather rare.

How To Take Care of Pregnant Guppies?

Pregnancy is a sensitive period in a guppy’s life, leaving it vulnerable to a variety of factors. The female guppy will require special living conditions to carry its pregnancy to term. Here’s how to approach the situation and make your guppy as comfortable as possible:

  • Prepare a breeding tank – You should set up a new tank as soon as you notice signs of guppy pregnancy. Just look for the inflated abdomen or the pregnant dark spot on the lower belly, towards the tail. The breeding tank should provide similar living conditions to the main one, including water parameters, oxygenation, decorations, plants, etc. This tank will be the fry’s home for the following several weeks of their lives.
  • Eliminate the stress factors – As I’ve explained earlier, several things can stress guppies, including predatorial tank mates, improper water quality, poor oxygenation, illness, etc. Identify these factors and address them properly wherever possible. This is key to providing guppies with a healthy, stable, and secure environment to carry on their pregnancy in peace.
  • Control the water parameters – Temperature, oxygenation, water flow, overall cleanliness, all these factors need to remain stable 24/7. Guppies don’t fare well with fluctuating water values, causing them to experience stress and lowering their immune system. Having a filter and constantly monitoring the various water parameters will help immensely provide guppies with a safe, comfortable, and balanced habitat.
  • Ensure proper food – Your guppies’ diet is key to improving their quality of life, preventing illness, and keeping them healthy and energetic. Guppies require a diverse diet consisting of plants and animal-sourced protein and fats. I’ve written several articles on the subject that you can draw inspiration from.
  • Eliminate deformed and sick fish – I suggest getting rid of guppies with deformities like bent spine syndrome or other conditions that they could pass on to their offspring. This will keep the gene pool clean and healthy.

Can Dead Guppies Give Birth?

Yes, that can happen, so don’t dispose of your dead pregnant female immediately. If the female dies during labor, allow the process to run its course. The fry will be delivered, and they will live. The situation changes if the death occurs hours or days before the delivery.

In that case, the fry will die along with their mother, and there’s nothing you can do.


Guppies are prolific breeders, with only one female capable of delivering hundreds of fry throughout the year.

If you’re into selective fish breeding, guppies are the ideal candidates. I’ve already written a comprehensive article on selective guppy breeding if you’re interested in the details and need guidance.

avatar Noah
I’m Noah, chief editor at VIVO Pets and the proud owner of a playful, energetic husky (Max). I’ve been a volunteer at Rex Animal Rescue for over 2 years. I love learning and writing about different animals that can be kept as pets. read more...

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