How Long Do Guppies Take To Grow? (And How To Help Them)

You may be wondering, ‘How long do Guppies take to grow?’ well, this article is going to take you through the growth stages of Guppies. It explains everything you need to know, how you can help them grow, factors that may cause them to stop growing, and how to ensure they live their full life cycle. 

If you are new to fish-keeping or are interested in adding Guppies to your ever-expanding personal aquarium, it is important to know everything there is to know about these colorful fish in order to help them thrive. Guppies can be a good starting fish as they have simple needs and are easy enough to take care of. 

How Long Does It Take Guppies To Grow From Fry To Adults? 

It will take around 6 months for a guppy to grow from fry to a mature adult, during this time they will where they will grow to between 4-6cm. During this time, they’ll go through four stages: fry, juvenile, young and adult.

What Are The Guppy Fry Growth Stages? 

There is a range of different stages when it comes to your Guppy’s growth, and knowing each stage is going to help you know how you should be looking after them.

Fry Stage: 

When Guppies are born, they are only about 0.6mm in length! They are able to swim on their own accord, and instinct will set in, so they’ll attempt to find the best hiding spot in the tank.

This is down to the natural instinct of hiding from predators. If you have a mix of adult Guppies and fries, it would be beneficial to separate them, which we will go on to explain later in this article! Overall, the Fry stage will last for about a month. 

(Do you want to know whether guppies eat their babies and how you can protect them.)

Juvenile Stage: 

After just one month, the Guppies enter what we call the juvenile stage. This stage is crucial for growth, so it is important to ensure you have the right information to help them. Female Guppies grow larger than male Guppies, with both averaging 1.2-2cm.

Another difference between males and females is that the female’s tails will be bigger than the males! It is also at the juvenile stage; you will see the Guppies’ colors starting to show! Make sure you provide the best food and care possible at this stage, as it is the most important for their growth. 

Young Stage: 

In the third stage or ‘Young stage’ at two months old, Guppies are now sexually matured. As previously stated, if you do not want to breed your Guppies, now would be the time to separate the males and females. 

It is also at this stage that you should stop feeding Guppies any fatty foods, as this would cause them ill health. With the right food choices for your Guppies, it will enhance their color! 

(Do you want to know how to selectively breed your guppies when they’re sexually matured? then this is how!)

Adult Stage: 

How long do Guppies take to grow? Well, the last and final stage of Guppy growth is achieved at 6 months old. They will grow to their full size of between 4-6cm, sometimes the male having longer fins and tails than the females.

They do not become infertile until they are between 1.5 to 2 years, so again, to clarify, they must be separated if you do not want them to breed! At this stage, they will need a good diet high in protein, which you should continue for the length that you own Guppies! 

What Can Stop A Guppy Growing Properly? 

So, now we know the different stages of growth when researching ‘How long do Guppies take to grow?’. It’s important to understand the factors that may stop them from growing properly. Here are some things to take into consideration when owning Guppies. 

Tank Size

The size of the tank for Guppies is crucial in how long and how much they grow. Surprisingly, a big tank can cause just as many issues for the Guppies as a small tank can.  

Firstly, the problems with a small tank are self-explanatory, the Guppies don’t have enough room, and that depends on how many you have. If you only have a couple, then you don’t need a large tank; however, having more Guppies means you will need more space, no matter how small they look at first! 

(Find out how many guppies you can keep in a 5 gallon, 10 gallons, and 20-gallon tank.)

On the other hand, having a large tank poses the problem of the Guppies expelling more energy to try to find food. The energy they lose by trying to maneuver around a large tank should actually be used for growth within the first three stages of their lives.  

Breeders also may use breeding boxes to keep Guppies within the first month of life; however, this cramped space is also detrimental to their growth. It is recommended not to use breeder boxes! Especially if you want your Guppies to grow and live to their full potential. 

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Water Volume 

This issue goes hand in hand with the problems of a large tank. The large volume of water means the Fry has to swim for increased distances to try to find food that would be easier to find in a small tank. Again, too little water volume, and you have too many Fry in a small amount of space, think of it like having a load of newborns in a studio apartment; it’s not enough space for them to grow in! 

Adult Guppies

A cause for concern can also be the adult fish when you are bringing up Guppy fry! Along with many other fish, Guppies aren’t opposed to eating their young! This could be worse if you also have a tank with a range of different fish.

We know that when Guppies are born, they seek out hiding spots automatically due to their natural instinct. If you have a community tank that contains any pregnant fish, this would be especially concerning for the Guppy Fry as they are even more likely to be eaten! 


As previously explained, the tank size can impact your Guppies and the way in which fries grow. However, another thing to take into consideration is the upkeep of the tank. Water needs to be changed frequently; otherwise, it attracts parasites.

Temperature and filtration systems are also important. Although Guppies are renowned for being a low-maintenance fish breed, it is important to think of the extra expenses that are involved. Not accounting for these will lead to issues for the Guppy Fry’s growth or even their lives as a whole.  


As with everything, the types of food you give your Fry are important. As with ourselves, if the Guppies are not fed a varied diet that will promote growth, you could face some issues later on. The amount of times a Guppy needs to be fed is also important.

Feed your Guppies too little, and they enter starvation mode and are malnourished, but also too much food can cause significant issues. This includes a build-up of rotten food in the tank, which leads to high ammonia levels, low pH levels, mold, and even blocking the filters, to list just a few problems. 

How To Help Guppies Grow? 

Fortunately, there are a lot of things you can do to help your guppies grow! So here’s what you can do to give them the best chance to thrive!


Tank size is hugely important when thinking about how long it takes Guppies to grow and should be accounted for as one of their basic needs. First, you need to assess how many you would like to keep. Are they going to be in their own tank, or will it be a shared tank with other fish?  

If the answer is in a shared tank, you need to be aware that you may lose some Guppies as your other fish can and may eat them. However, if you choose to have a separate tank or your first tank of just Guppies, remember they will start to breed after two months!

This may encourage you to split the male Guppies from females, or you will have a lot more than you first expected… if they don’t eat them first!  

(Find out the best ways to keep males and females together.)

Again, whichever you choose, remember that too big of a tank can cause the Guppy Fry to expel too much energy looking for food, but a small tank may not give them enough room to grow. It would be best to stick to the ratio of 1 gallon of water per inch of Guppy, so this equation would determine your tank size.

Aquatic retailers will also be able to advise you on good tank size; however, it is very important you do not take advice for keeping them in a breeding box! 


Feeding Guppies is really important, like any living thing, for growth. When feeding Guppy Fry, it would be wise to feed them between 5-8 times a day. More often than not, increased feeding will promote better growth.  

When they get to the adult stage and to their full growth potential, it is then recommended to feed them between 1-3 times a day. Ensure that you only feed them a small amount each time to ensure the food does not become foul in the tank also.

You should be able to gauge the quantity from this. However, a good way to find out how much to feed your Guppies would be to count how many flakes they eat within 2 minutes. Anything left will mostly never be eaten by them, and you don’t want to cause issues for the environment. 

The types of food you want to feed Fry are baby brine shrimp, micro worms, daphnia, or vinegar eels. If you purchase Guppy flakes, ensure they are high-quality crushed flakes, so they are small enough for the Fry. 

As they progress to the adult stage, feed them a mix of freeze-dried fish food, vegetables such as lettuce, cucumbers, and peas, and again high-quality fish flakes.  

(These are the 8 best foods for guppies as well as what they normally eat.)


Maintenance of your tank is fundamental in figuring out how long guppies take to grow. It is very important to do regular tank checks and weekly water changes to ensure that your Guppies stay healthy.  

Gravel vacuuming is a must, along with ensuring the upkeep of the filtration system, as you don’t want to harvest any disease or parasites. It is recommended that you use a water conditioner to promote healthy living conditions for your Guppies. The water conditioner will also remove any chlorine or chloramine present. 

These tips can help to make sure nothing unfortunate happens to your Guppies. If you do find that your tank or Guppies have become affected, it is best to treat as quickly as possible for minimum damage. 


When Guppy Fry is born, they seek out hiding spots as a natural instinct to hide from predators. This means that your fish tank should contain live plants such as Guppy grass. If you choose to use a mixed tank, this will also provide protection from other fish, but it also cannot guarantee it.  

Guppies need plenty of light to maximize growth and maintain livelihood. To support this, use artificial lamps; the lamps should be kept on for a maximum of 16 hours and no less than 12 hours a day. This should be continued even when they are fully grown! (Here’s everything to know about how much light guppies need.)

Another way to help your Guppies grow in their tank is to do a water check daily. Along with the weekly water change, monitoring day by day means that you can tackle any problems that may arise quicker than just monitoring your weekly change. You should also remember that the water temperature should be between 24-26 degrees Celsius and ensure the pH level is between 6.8-7.8. 


To conclude, we now know that to grow to the adult stage, it takes them around 6 months. However, the size, color, and health of the Guppies are down to how well they are kept.

As with any living thing, we need to consider basic needs such as food, shelter, sanitation, and space. Guppy Fry must be fed between 5-8 times a day, then when fully grown, just 1-3 times a day. Ensure that at all times, you are monitoring the tank and water cleanliness, and the temperatures are correct along with the pH level.

We also need to ensure that the Guppy Fry has enough space to grow, move, and hide if necessary, so tank size and water volume matter! Hopefully, this should answer most questions surrounding, ‘How long do Guppies take to grow?’

We recommend following these guidelines as they provide knowledge of how to avoid problems and will ensure that your Guppies grow to the right size and live a happy life!