How Many Guppies in a 10 Gallon Tank? (Mistakes To Avoid)

If you’re wondering how many guppies you can keep in a 10 gallon tank, then you’ve found the right article! In this article you’ll also find out how to calculate how many fish you can keep altogether, whether the gender matters, and when to worry about the tank becoming overcrowded!

So keep reading to find out everything you need to know!

How Many Guppies in a 10 Gallon Tank? 

Guppies vary slightly in size according to their type and age. For a single guppy, you need at least one gallon for every inch of fish there is. With this in mind, you can then work out how many guppies you can easily keep in there.  With this in mind, you can safely come to the following answer!

You can add 5-6 guppies to a 10 gallon tank as guppies generally grow to about 1.5″ – 2″ in size. With that being said, if you’re new to fishkeeping then you should consider keeping 3-4 guppies to reduce the chance of something going wrong.

How Do You Calculate How Many Guppies You Can Keep in a 10 Gallon Tank? 

To calculate how many guppies for your tank, the general rule of thumb is one gallon of water per one inch of fish. Therefore, in a 10-gallon fish tank, you can add the equivalent of 10 inches worth of guppy.

Why 10 Gallons Is Smaller Than You Think

However, it’s also important to remember that you can’t keep a fish tank empty and boring. The key to keeping guppies healthy is to provide the means of activity. There are more objects that you should place in your 10-gallon tank. This can include the following: 

Filter And Heater

First of all, when you’re keeping guppies in a tank you also need to make sure you’re keeping a filter and heater in the tank with them as well. While some filters can hang on the back of the aquarium, most will be placed inside the aquarium along with the heater. Both of which will lower the amount of space in the tank.

Toy Buildings 

Props such as houses, castles, monuments, caves, etc., are a popular option for guppies. These add to the beauty of your aquarium and are fun for your guppies, too. Their shade is also a source of comfort for young fry and pregnant guppies. 

Tank Mates 

Yup, it’s better to keep a variety of tank mates in your guppy tank, too. Usually, the following are considered the best tank mates for guppies

Guppies are normally peaceful, so they can get along with a number of tank mates. Just be sure that the mates you consider have a calm temperament and do not pick a fight with the guppies. 

They should also be comparable in size with their fellow guppies. If you keep tank mates, you will need to keep 2-3 guppies, and you should also consider upgrading to bigger tank, as it will likely become overstocked.

Tank Plants 

A fish tank with lush green plants is an absolute treat to the eyes. most aquarium plants are easy to maintain and make the tank comfortable for guppies, especially the young ones. 

(Find out some of the best plants that stay small you can keep in your aquarium.)


Lastly, a tank shouldn’t kept empty at the bottom. You should fill it with sand, gravel or aquarium soil. Not only will this keep your tank looking nice, but it will also help the beneficial bacteria colony grow in your tank which is vital for the nitrogen cycle.

Does The Gender Of The Guppies Matter? 

Female adult guppies normally grow up to almost 2.5 inches in length. By contrast, male adult guppies are smaller and grow up to 1½ inches in length. However, if you’re going to keep them, normally, it’s best to keep males and females together. (Here’s a helpful article on keeping male and female guppies together.)

How Many Male And Female Guppies In A 10 Gallon Tank?

When you’re keeping male and female guppies together, no matter the size of the tank you should always keep 1 male guppy for every 2 female guppies. Doing this reduces the chance of aggression occurring, as well as reducing the amount of harassment the amount of females get to breed.

What Will Happen If You Add Too Many Guppies? 

Overpopulating a fish tank, no matter how large, is never a good idea. If you put more than 5-6 guppies and tank mates in one ten-gallon tank, here’s what can go wrong: 

Unstable Water Parameters 

Guppies need healthy, balanced chemical composition in their water. It’s their source of life, and if contaminated, it can kill them. With too many guppies, there is a chance of ammonia and nitrite spikes, which can sicken the guppies. In worse cases, weaker guppies may even die! 

The Tank Will Get Dirty Often 

Fish excretion remains in the tank unless you clean it. A tank with sufficient water and a smaller number of guppies can stay clean and clear for longer. Their feces will disintegrate easily, and be removed by the filter. On the opposite side, a tank with too many guppies will get dirty too quickly and may even be a cause of diseases. 

Aggression and Killing 

If guppies aren’t given enough space in the water, these harmless creatures can become aggressive. They may end up killing other tank mates, guppies, or fry. 

(Find out more about aggression in guppies.)

Deformities and Growth Issues 

Malnutrition is another common problem that you may face in an overcrowded guppy aquarium. Guppies may have to struggle for food, sufficient oxygen, and hiding places. If guppies don’t get a sufficient amount of tank volume to themselves, it can also hinder their growth and cause health issues. 

(Another common reason this can happen is when they aren’t bred properly. Here’s a guide on how you can selectively breed your own guppies.)

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Will the Tank Become Overcrowded Due to Breeding? 

If you purchase a mix of male and female guppies, they’ll most definitely mate every now and then. If a guppy conceives every other month, that can be too risky in a ten-gallon tank. Guppies can deliver anywhere between 10 and 120 guppies. 

Each young fry is about one-fourth of an inch at birth and takes six months to fully mature. To reach the size of two inches, guppies grow at an average of 0.3 inches every month. So, either avoid having male and female guppies in the same tank or keep a separate tank for the fry. 

(Want to know more about how long it takes guppies to grow?)

If you want to grow a family of guppies as a beginner, you should wait for some time. Try keeping only one gender at first. Once you understand how to keep guppies, bring in the other gender to begin breeding.

Simultaneously, make arrangements for a fry tank because guppies mate frequently and quickly. Keep an eye on your pregnant guppies and place them separately in a breeding box when they’re about to deliver. 

A breeding box will keep the pregnant Guppy isolated from other adult guppies, too. When the fry are born, place them in a separate tank, and quickly make arrangements to move them somewhere else, as they will begin to breed too!

Is It Possible To Add More Guppies To A 10 Gallon Tank?

Whilst it’s definitely not recommended, it is possible to add more guppies to an aquarium, however, there are a few things you’ll need to do.

Use A Good Filter

The most important thing you can do is make sure you’re using a powerful filter in your tank. You should opt for an external filter over internal to maximise space.

On top of using a good filter, make sure there is plenty of biological media in the tank to help harbor beneficial bacteria.

A good filtration system in your guppies tank is essential for removing fish waste and toxins, as well as housing good bacteria.

Test And Change The Water Regularly

As well as making sure that fish tank filter is good enough, you should also be testing the water and changing it regularly as well! With more fish, it’s much more likely that something is going to go wrong, so testing the water regularly will help you keep an eye on any spikes in the tank.

Add Live Plants

As well as improving the filter quality and checking the water you should also add plenty of live plants. Thy are going to help keep the water clean, while also giving all the guppies in your tank plenty of places to hide and rest if they need too!

If you’re not sure what plants to add, i’d highly recommend:

  • Java fern
  • Anubias
  • Duckweed
  • Amazon sword
  • Amazon frogbit
  • Hornwort
  • Guppy Grass
  • Water Lettuce
  • American Waterweed

Remove Any Uneaten Food

You should also make sure that you’re removing any uneaten food from the tank as well. As soon as your guppies are done eating. When you’re keeping more guppies than a 10 gallon tank can handle together, the ammonia levels can rise incredibly quickly. One way with dealing with this efficiently is by ensuring there is minimal waste in the tank.


Here are some frequently asked questions that people have about how many guppies they can keep in a 10 gallon tank!

How Many Guppies Should Be Kept Together Generally?

You should keep at least three guppies in a an aquarium that is a minimum of 5 gallon in size. Simply increase the tank size according to the number of guppies you intend to keep more. (And you should always keep 1 male guppy for every 2 female guppies.)

How Often Do Guppies Breed?

Female guppies can produce offspring monthly (once every 30 days). If the conditions are favourable and the tank contains male and female guppies.

How Many Guppies In A 10 Gallon Tank With A Betta?

You should never keep guppies in a 10 gallon tank with a betta because the chances are your betta will end up attacking them. In larger tanks, you can try keeping female guppies with male bettas, or female guppies with female bettas.

However, the chances of success will vary massively depending on the temperament of your fish.

Can You Keep 2 Male Guppies Together?

It’s not recommended to keep two males guppies together as they’ll end up fighting. Instead you should keep your guppies in a 2:1 or 3:1 male to female ratio.

How Many Guppies & Tetras In A 10 Gallon Tank?

A 10 gallon tank may be a bit small for both guppies and Tetras, so you should consider a 15 gallon tank or larger.


There’s no doubt about the fact that guppies are a fascinating fish breed. These fish breed quite easily and perfectly encapsulate the beauty of marine life. So, if you’re looking to brighten up your house with a nice aquarium, getting guppies is the way to go.   

If you buy a ten-gallon tank, you can easily house 5-6 guppies inside, however, beginners should only try keeping 3-4. I hope this guide helped you to figure out how to keep your 10-gallon aquarium healthy for guppies without overcrowding them!

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