Gestation Period for Guppies – How Long are Guppies Pregnant?

Guppies’ gestation period will vary between 21 and 35 days, with the average sitting at around 25 to 26 days. Several factors will influence the gestation period in guppies, some of which you can control while others you can’t.

Today, we will discuss guppy pregnancy, looking into what you can do to either prolong or reduce the gestation period. We will also analyze the factors that may affect your guppies’ pregnancy.

How To Speed Up Gestation in Guppies?

Many guppy breeders seek to accelerate their guppies’ birth rates, which includes shortening the gestation period. You can achieve this via two core methods:

– Increase the water temperature

This is a sensitive topic since guppies prefer stable waters with tropical temperatures. The ideal water temperature should remain between 72 and 80 F with only slight variations. The guppy can cope with values outside the ideal parameters, but not for long and not with wild variations.

Increasing the water temperature slightly can reduce the gestation period since the female is more comfortable with her surroundings. Its instinct will tell her that the increased water temperature signifies a stable and flourishing environment.

Just make sure you increase the water temperature gradually over the course of several days and never too much. Hotter waters will also have lower oxygenation, which can hurt your guppies in the process.

– Increase the protein content in the guppy’s food

An abundance of protein-rich foods will signal the female that the environment has plenty of food for its offspring. This can decrease the gestation period by 5 to 7 days.

The problem is that it’s not a failproof method. Sometimes it works, sometimes it doesn’t. There’s no harm in trying, provided you don’t go overboard. Guppies don’t cope well with excess protein and fat since it can quickly lead to overfeeding and health issues.

How Many Fry Will a Guppy Deliver?

The number of fry that can result from a pregnancy will vary wildly. Expect anywhere between 2 and 200 fry, depending on the diet, environment, the female’s genetic makeup, water conditions, etc.

If you want to keep as many fry as possible, I suggest moving the pregnant female into a separate tank when labor kicks in. This will protect the fry from the cannibalistic adults that will not shy away from eating them.

I also advise moving the female back into the main tank for the same reasons. After all, female guppies are not particularly famous for their maternal instincts.

How To Identify Guppy Pregnancy?

Identifying pregnant females as soon as possible saves you a lot of headaches along the way. Numerous signs will come with the pregnancy, some behavioral, while others strictly physical.

The most compelling ones include:

  • The inflated belly – All pregnant guppies will display a fuller and more inflated belly, especially towards the end phase of the pregnancy. However, this sign alone can signify a variety of causes, including constipation or fish illness. This is why you shouldn’t rely on this sign alone to determine whether your guppy is pregnant or not.
  • The pregnant spot – This is a universal sign that all guppy females will display. The so-called pregnant spot will become visible in the rear part of the abdomen. It’s a darkened area that shows the presence of developing fry in advanced stages of pregnancy. At this point, moving the female into a safer and more comfortable environment, away from the main guppy population, would be ideal.
  • Behavioral signs – Your pregnant guppy female will display several behavioral changes during the pregnancy. This includes, constantly looking to hide between plants and rocks, swimming in place, showing lowered appetite, rubbing against obstacles.

These changes occur in late-stage pregnancy, but you should already know what’s going on by now.

If you’ve already identified the pregnant guppy, I suggest keeping an eye on her. Pregnant guppy females can become stressed if chased by males or dealing with improper water conditions. It would be ideal for moving the pregnant guppy into a separate environment towards the later phase of its pregnancy.

Removing the female from the stress-filled environment will ensure the success of the pregnancy. It will also provide the upcoming fry with a safe and controlled environment to grow big, fast, and healthy.

Why Is My Pregnant Guppy Not Giving Birth?

Several reasons may cause your pregnant guppy to postpone the delivery. These include:

  • Colder waters – As the water temperature drops too much, your guppy will experience distress, causing it to postpone the birth. The guppy will also appear less active than usual and even display signs of stress.
  • Insufficient food – Insufficient or improper food can delay the birth. You should feed your guppies a balanced, varied, and healthy diet consisting of live food, plants, vegetables, and pellets and flakes whenever necessary. Ensuring the optimal nutrient intake is key to helping your guppies remain healthy and active throughout the year.
  • Stress – Guppies can experience stress for a variety of reasons. These include aggressive tank mates, being bullied by pushy males during mating, improper water conditions, etc. Whatever the cause may be, identifying it fast will allow you to take proper action in time.

If you ignore these problems, your guppy may lose the pregnancy or even die in the process. My recommendation would be to monitor the tank dynamics and water quality continuously throughout the day. Some problems may aggravate fast and wreak havoc among the guppy population.


The gestation period for guppies will vary depending on numerous reasons. Some are benign, like genetic predisposition, while others can be more serious. Some of the latter ones include improper dieting, unfit water conditions, guppy stress, illness, etc.

To keep things on the safer side, I suggest moving the pregnant guppy into a breeding tank as soon as you observe the first signs of pregnancy. You can keep it there, along with other pregnant females, until it gives birth.

The resulting fry will have all the space they need to grow and develop into strong and healthy adults.

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...

Leave a Comment

Your email address will not be published. Required fields are marked *