Guppy Fish Growth Stages


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Guppies have a really simple lifecycle. In this article you will find the different growth stages of guppies. I will tell you how to care for your fish in the different stages in order to grow big, colorful and healthy guppies.

How big do guppies get? Female guppies can get up to 2 inches (5 cm), while male guppies up to 1.5 inches (3.8 cm) in size. If you follow my advice, which I present in this article, you will be able to get your guppies at full size in about 5-6 months.

Guppies are livebearer fish; they do not lay egg, so the larval stage is missing completely.

The male guppy fertilizes the female. The baby guppies will develop inside the female’s body for about 30 days, until they are born.

Fry Guppy

Guppy Fry

Guppy fry are free swimming right from the start. Once they are born, the first thing they do is to look for a place to hide. They are deformed at the beginning, but after couple of hours their body straitens and become strong enough to start feeding.

Guppy fry are small; they are about 1/4 inch (0.6 mm) in length. Most of the time adult guppies and bigger fish will eat them. To save your fry, you might want to separate the pregnant guppy female from the rest of the fish, or provide enough hiding spaces, such as live plants, to your fry.

Guppy fry will eat the same food as their parents. However when you feed flake foods to them, make sure you crush it up into powder. Feeding live food is also beneficial to your guppy fry. Baby brine shrimp are the best food you can give them. The yolk of a hard-boiled egg will also help significantly in their growth.

Leaving the light on for 12-16 hours a day for fry can also contribute a lot to their growth.

Frequent water changes are a must, especially if you feed your fry multiple times a day. Some guppy breeders do complete water changes every day or every other day.

At about one month, guppy fry become juvenile.

Juvenile Guppy

Juvenile Guppy

In the juvenile stage, they start gaining some color and you can distinguish the different sexes. Females are much larger and their gravid spot are already visible, while the tale of males are smaller and start coloring up. The gonopodium of male guppies start forming.

The juvenile stage is one of the most important in the life of a guppy. It is important to give them the best food and water. At this stage you can feed brine shrimp, blood worms, high quality flakes, spirulina and plankton pellets and beef hart.

Guppies in the juvenile stage are between 1/4 and 3/4 inches (1.2 to 2 cm) in length. At around 2 months they start maturing sexually and they become young guppy.

Young Guppy

Young Female Guppy

Young guppies start being sexually active at around 2 months old. Selective guppy breeders separate the males from the females in the juvenile stage. Keeping the males separated from the females will also contribute to their growth, because they are only focusing and feeding and not reproduction.

Feeding young guppies is a bit different than feeding guppy fry. You want to lower the fat intake and offer them more protein and greens. Brine shrimp should be still their main source of food. Spirulina and plankton pallets will help develop a more intense color.

At around 6 months old, guppies become adults.

Adult Guppy

Pregnant Adult Female Guppy
Adult Male Guppy

At around 6 months, guppies reach their adult stage. Depending on their genetics, and conditions an adult female guppy can reach about 1.5-2 inches (4-6 cm).

Their growth will stop or slow down significantly. The fins and tail of male guppies might grow longer over time, depending on their genes.

To keep your guppies healthy and colorful, you should still feed them a variety of food. Their main food should be flake food high in protein. Avoid feeding them fats, because it is bad for their health.

Guppies can live around 2-5 years. At around 1.5-2 years old adult guppies become infertile and they are not able to reproduce anymore.

Very Old Female Guppy

Wrapping Up

Now that you know about the different guppy growth stages, and know how to feed the fry, juvenile and adult fish, go ahead and start breeding guppies.

If you might have any questions, please ask me in the comments below. Also check out my other articles to learn more about guppy fish.


Updated: July 15, 2019

Questions & Answers

    1. avatar

      Hi Darrel. I recommend keeping baby guppies in a breeding or mesh box for up to one week. It would be ideal if you could separate the babies to a new tank, where they can grow. If you don’t have the possibility to run multiple fish tanks, you can release the babies into the main tank after one week, but provide them with hiding space. Add live plants, such as Java moss or Guppy grass so the fry can hide and be safe.
      Before you release the baby guppies into the tank, feed the parents well, so they will not go after the fry. Release all the fry at once, to lower the changes of the parents are eating them.
      If you have a community tank with angelfish or goldfish, you might not want to keep the babies until they get bigger. Angelfish will eat the small babies no matter you feed them or not. Goldfish have a huge mouth, so they are also a danger for the fry.

    1. avatar

      Yes, you can keep guppy fry together with other small fishes, just make sure you provide them with enough cover and hiding spaces through aquarium plants.

  1. Polyniki

    Hello Fabian, thank you for the info! I was wondering, do Guppies change look when they get older? One of my most fertile females, who used to look fat and bright, stopped getting pregnant some months ago and although she was still very active and healthy, recently I noticed that her tail had sunk and she looked as if she had shrinked in size. Also her skin was kind of greyish. Today I found her dead 🙁 I was wondering if this was simply old age? Thank you!

    1. avatar

      When guppies become infertile, it is a sign that they are getting older. It is normal, that guppies that produce lot of fry will get consumed faster. It is also normal that they lose their color when they get older.
      The aging in guppies can happen really fast, is just few weeks. Their organs and immune system will become weaker and eventually will become sick and die.
      I’m almost sure, that your female guppy died due to old age and due to very active reproduction. This is their life cycle, which is normal.
      Though, I recommend to monitor your other guppies, just to eliminate the possibility of any potential disease.

  2. Polyniki

    Thank you for your answer! Actually she was not dead yet. I thought she was because she was laying on the side and her back was bent to the side too, but she was still alive and survived another 24 hours like this, barely swimming (on her side, spine bent to the side). All my other guppy are doing great but I am still concerned if this might have been some disease. I checked your page on common diseases but nothing suits these symptoms. Her belly was not swollen, no signs of infection or injury. Any clues? Thank you!

    1. avatar

      It is really hard to tell from your description if there could be any disease that affects your guppy. I think she has become week due to giving birth so many times.

  3. Hi, am I correct in assuming a tank will easily become over populated if you have both male and female guppies? What do you do to try to limit this if you only have one tank and can’t separate the sexes?

    1. avatar

      Hey Sarah! Keeping male and females guppies together can result in overpopulation. I’ve wrote a guide on how to control guppy population – check out the linked article.
      If you don’t have the possibility to keep males and females separately, I recommend adding a female betta wish to your tank. The betta will hunt down the small fry and your guppy population will be under control. Some fry might get along, but that is ok, because some of the adults will die off sooner or later, so the new guppies will take their place.
      This is not the way I would do it, but for your setup this might be the best option.

  4. Why guppies’bodies are rolling downward when they are swiming and within next 2 days they will die.. Body turns to pale color also

    1. avatar

      I think this is a swim bedder problem which can be caused by ammonia poisoning. Check water parameters, and make sure ammonia and nitrite levels are at 0 ppm.

  5. Hoang Nguyen

    Hi Mr Fabian , i have a question . How old are the male and female guppies? At how many months can they mate with each other, if they mate at a young age, does it affect the quality of their fry?

    1. avatar

      Hi Haong! The sexual maturity in guppies really depends on their growth rate. Guppies can become sexually active at 3-4 months old. The quality of fry are not affected in this case, though the quantity is significantly lower. A young and small female will only produce 4-10 fry. While a 6-8 months old female guppy can drop up to 100 fry.
      If you want to breed guppies, I highly recommend you separate males from females at 5-6 weeks old and you wait until they get at 5-6 months age. At this age you can already see which males and females you want to reproduce and you choose only the best one for reproduction.
      I found out that guppies will grow faster if males and females are separated. Also tank size and food quality is an important factor in their growth rate.

  6. If a 1 month female guppy is in a tank with another 1 month guppy and a 5 month guppy will she get pregnant or is there more time before I have to separate them.

    1. avatar

      Guppies usually reach sexual maturity at around 3-4 months. So there is still time left to separate them.

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