How to Tell if a Guppy is Pregnant?

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Guppy pregnancy may appear as alarming to novice guppy keepers. This generally happens due to the changes in a female’s body and behavior as the labor approaches. After all, there are many health conditions with symptoms resembling those of pregnancy, at least in the initial phases.

With that in mind, here are the guppy pregnancy symptoms to look out for:

Growing Belly

Guppy females are generally larger than males with more protruding bellies. These differences will become even more obvious in pregnant females, whose bellies will inflate to impressive proportions. 

Many inexperienced fish keepers will mistake early pregnancy for constipation or other digestive issues that come with an inflated belly. Over time, you will learn to differentiate between pregnancy and other health problems. After all, guppy females will get pregnant monthly, each time displaying the same physical symptoms and behavior.

The Gravid Spot

This is one of the clues to look for when assessing the cause of your guppy’s larger belly. The gravid spot is simply a darker area towards the rear of the female’s abdomen. This area will initially be brownish in color, darkening as the pregnancy progresses.

When the labor approaches, the gravid spot will turn completely black. But what is the gravid spot?

It’s nothing more than the reflection of the fry’s black eyes through their mother’s abdomen. A truly magical though if you ask me.


Behavioral Changes

Pregnant females will display more aggressive and irritable behavior during pregnancy. This behavior may exacerbate as the labor approaches. You may see the female chasing away the guppy males and even females lower on the pecking order.

When the labor is near, the pregnant female will stop eating and start looking for hiding spots. This instinctive behavior guides the female to deliver the fry in safety, far from the eyes of other adult guppies.

Don’t get it mistaken, however, since female guppies are not famous for their maternal instincts. They will abandon their fry immediately after birth. That is unless they decide to stick around to eat them, of course.

Visible Color Changes

The female will change its coloring during the pregnancy phase. This sign, in particular, could alarm inexperienced guppy keepers since color changes in guppies are generally a sign of sickness.

If you notice that your females’ colors start changing, look for other signs of pregnancy. A more prominent belly and even the appearance of the gravid spot should be enough to confirm the pregnancy.

Pregnant Guppy Signs of Delivery

Your female guppy will display a variety of signs when the labor kicks in. The most common ones include:

  • A bulkier appearance – The female’s body will round up nicely, with the abdomen gaining impressive proportions. In some cases, the abdomen will inflate so much that it will appear almost square.
  • A darker gravid spot – The gravid spot will darken gradually as the pregnancy progresses. When the labor approaches, the gravid spot will be completely dark and larger in size, taking up 50% or more of the abdominal area.
  • Static swimming or immobility – The female may either swim in place or remain still for longer periods of time. This is a sign that the labor has begun.
  • Rapid breathing and shivering – The female will arch its body, lift its tail, and move almost spastically in place. This signifies that the labor pain has set in, and the fry may begin to arrive soon. The female may also display rapid breathing as if it were gasping for air. Don’t worry, this is normal behavior for delivering guppy females.

The female may also refuse food or spit it out when nearing labor.

How Long Are Guppies Pregnant For?

The pregnancy phase in guppies can last between 20 to 35 days. More realistically, you should expect the female to deliver within 25 to 30 days after mating. The duration of the pregnancy will vary depending on numerous factors, primarily environmental conditions.

Females tend to deliver the fry sooner if the water temperature is slightly higher than normal. This will signify to the female that the environmental conditions are optimal for its fry.

It will also help to provide the female with a varied and consistent diet and remove all stress triggers that could affect its pregnancy. Guppy females can become a bit more sensitive during pregnancy, displaying more aggressive behavior and attacking other fish.

The situation can worsen when you have multiple males who want to mate, even with pregnant females, stressing them out in the process.

Do Guppies Get Pregnant Without a Male?

Confusingly enough, the answer is both yes and now. Technically, guppy females need a male to reproduce. Unlike other animals, like some species of snails, for instance, guppies can self-impregnate.

The problem is that it could appear as such to some people, especially if they don’t know how guppies function. In many situations, the female can get pregnant repeatedly even when there hasn’t been a male present in the tank for months.

Actually, guppies can get pregnant for up to a year or more without any male around them. This is where the guppy female’s biology comes into play. Guppy females have been biologically hardwired to develop a safety mechanism, allowing them to get pregnant even if there are no males in their environment.

The guppy female can store the semen of multiple males inside her and use some of it every month to self-impregnate. They achieve this by storing the male’s semen after the copulation. This can create the illusion that guppy females don’t need males to produce offspring.

It’s also what explains how people purchasing their guppy females for their female-only tanks will have them getting pregnant months on end. That’s because the females have already mated with the males prior to people purchasing them.


Guppy pregnancy is relatively easy to spot once you’ve learned the essential signs. What you do with your pregnant guppy depends solely on your goals. If you don’t care about the fry, allow the female to give birth in the main tank. The adult guppy population will eat most of the fry indiscriminately.

If, however, you want to save the fry for selective breeding purposes, move the female into a breeding tank when labor sets in. This allows you to save the fry and feed them an enhanced diet to boost their growth.

You can add them back to the main tank at 3 to 4 weeks of age.

Personally, I would quarantine the birthing female anyway for a couple of reasons:

Controlling the breed – Maybe you want to boost your guppy community with new and exhilarating traits, in which case controlling the fry population is a must. It allows you to assess the fry, save the ones with the desirable traits, and discard the rest.

Prevent overcrowding – Having several guppy females delivering dozens or hundreds of fry at once is never a fun experience. The tank will become overcrowded fast, leading to ammonia buildup and higher levels of nitrates. Without controlling the fry, the environment will soon become suffocating and even toxic for your guppy population.

Minimize the impact of transmissible diseases – Allowing the females to breed uncontrollably will overcrowd the tank and increase the risk of disease spread. One contagious disease will now infect the whole population faster since you will have fish roaming everywhere.

Consider these aspects if you decide not to quarantine pregnant females anyway.

Updated: December 10, 2021

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