Best Tank Size for Keeping Guppies

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Guppies aren’t large fish and don’t require huge tanks to live comfortably. Still, if you’re planning on keeping guppies, you need to know the best tank size for guppy fish.

Small tanks are always more problematic than large tanks. In a small tank, guppy fish will feel crowded and water parameters are much more difficult to keep stable.

Investing in a huge tank may not be a smart decision either as it can put a strain on your finances. Plus, a tank that’s too big can make it difficult for guppies to efficiently search for food.

Therefore, getting a tank that’s just right is the best way to ensure the comfort of your guppy fish and offer them an environment with stable water parameters.

In this article, I’ll talk about the best aquarium size for keeping guppy fish, the number of guppy fish that you should keep in an ideal tank, and what types of aquariums to avoid for guppy fish.

Minimum Tank Size for Keeping Guppies

10 Gallon Aquarium Kit
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The smallest tank size that you should pick for keeping guppies is 10 gallons. In your research about guppy fish, you’ve probably seen it mentioned that 10-gallon aquariums are the minimum tank size for guppies.

Indeed, a 10-gallon aquarium will comfortably hold a small guppy group of around 5 specimens or up to 10 guppy fish if you’re an aquarist with experience.

When stocking your aquarium, you should know that an aquarium that could otherwise hold 10 gallons will not hold the same water volume once it’s all set up. This is because of the additional aquarium equipment that’s required for these fish.

Equipment such as water filter, air pump, and decorations such as live plants and substrate will displace some of the water volume, resulting is less holding capacity that what the aquarium is rated for.

Therefore, if you’re going for the whole set-up (and you must unless you really know what you’re doing), I encourage you to opt for a larger aquarium.

If 10 gallons is the minimum tank size recommended for keeping guppies, what is the ideal tank size for guppies?

Ideal Tank Size for Guppies

40 Gallon Aquarium Kit
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If you’re looking to keep a larger number of guppies, you don’t mind splurging on a tank, you have enough space in your home, and you’re looking to create a highly comfortable environment, then a 40 gallon aquarium would be an ideal tank size for guppies.

A tank this size will ensure that there are no crowding issues and subsequent water chemistry disturbances because of the increased waste production and toxin accumulation.

A 40-gallon tank will also make it easier for you to decorate the aquarium with live plants, caves and other aquarium decorations and add all the equipment that’s required without having to worry too much about loss of water volume.

Water in a large aquarium is more chemically stable and not as prone to sudden ammonia spikes like a small aquarium would be.

It’s also true that a larger aquarium takes up more space in your home, it’s more expensive to put together (you’ll need to find equipment that can deal with the water volume, e.g. heater, air pump, etc.), and a bit more difficult to maintain.

If all these seem manageable things to you, then a 40-gallon tank will be a great way to set up a species-only aquarium or a beautiful community tank.

And since we’re on the topic of community tanks, it’s worth noting that guppy fish are sociable fish that should not be kept alone. Guppies love company, so do keep them together with other freshwater fish.

They’re also compatible with a large number of freshwater fish including platies, swordtails, mollies, otocinclus catfish, cardinal tetras, and many more.

When setting up a community aquarium, a 40-gallon tank can be an excellent starter tank. Do make sure you’re familiar with the water and dietary requirements of each fish and their compatibility with guppy fish or other fish you’re planning on adding to the aquarium.

How Many Guppies Can You Keep in a Fish Tank?

Aquarium overstocking issues are common among beginner aquarists. Too many fish in an aquarium will cause oxygen levels to drop and waste and toxins to accumulate. To avoid this, you should learn about proper aquarium stocking.

A good rule that has always worked for me is the 1 guppy per gallon rule or the 1 inch of guppy fish per gallon rule.

Remember that once an aquarium is set up it won’t have the same holding capacity as it would without all the equipment in it, so do factor that in when you’re making your calculations.

If you want your fish to be disease-free and grow without deformities, a spacious tank that offers them enough space to comfortably swim around can go a long way in keeping them healthy.

Beyond the number of guppy fish you can keep in an aquarium, you should also consider guppy female to male ratios.

Livebearers don’t waste any time reproducing and soon, your aquarium can be taken over by fry when you least expect it.

The best way to stay on top of these situations is to either be careful to have much fewer males than females (3:1 female to male ratio is the gold standard for guppies), keep only females, or stick with males only.

Having a males-only guppy tank can be a challenge because these fish will constantly be in competition and bullying can become a serious issue.

There are multiple ways to deal with unwanted guppy fry including adding a female betta fish to the tank (bettas are carnivores and will happily eat the fry), removing hiding places, and preventing breeding in the first place.

Therefore, to sum it all up:

  • The minimum tank size for keeping guppies is 10 gallons, this tank will comfortably house around 5 guppies;
  • The ideal tank size for guppies is 40 gallons, which can house a fair number of guppy fish along with other guppy compatible fish;
  • The 1 fish per gallon rule can be used as the standard fish stocking rule when it comes to guppies;
  • With guppies, female to male stocking ratio is also important, females should always outnumber males;
  • Unwanted fry should be dealt with as soon as possible to avoid overstocking issues;
  • Guppies should not be kept singly because they’re social fish that don’t thrive in solitude;
  • When adding other fish to the aquarium make sure they’re compatible with guppies.

I’ve seen photos and videos of guppies being kept in glass bowls, which can barely hold a few gallons of water, which brings us to the next point of my article:

Can You Keep Guppies in a Glass Bowl?

Glass bowls may look aesthetically pleasing and cool, but they’re a bad idea for fish, despite being targeted for fish keepers.

These glass bowls are usually 1-3 gallons, which is way too small for guppies. Guppies may not have a high bioload, but they still produce a fair amount of waste that would not go unnoticed in a bowl without a filtration system.

Besides the space constraints, water in small glass bowl is also extremely chemically unstable because the small water volume is unable to dilute the toxins that get produced.

Even if you consider getting a filter for a glass bowl, your options for filtration are extremely limited since filters are made for regular aquariums either won’t fit into the bowl or they’ll be too strong for it.

Therefore, if you’re thinking of keeping guppies in a glass bowl, just don’t. Guppies cannot be kept in a glass bowl because they will have a poor quality of life and they’ll end up dying because of unstable water conditions.

If you’re more fascinated by glass bowls than you are by guppies, then I recommend keeping snails or shrimp and create wonderful aquascapes, bearing in mind that these aquatic creatures can reproduce and colonize the bowl quite fast.

Some aquatic creatures are better suited for a glass bowl than guppies are, so do yourself a favor and skip the glass bowl if you’re considering keeping guppy fish or any other fish for that matter.


The best tank size for guppies will depend on many factors, but ideally following the aquarium stocking rules I discussed in this article will give you a good idea on how many guppies you can keep in a given aquarium.

Make sure you have all the equipment needed for a guppy fish tank, including a heater and an aquarium filter. Guppies prefer having live plants in their tank, especially that they’ll nibble on the soft algae that grows on them.

Make sure water parameters are stable in your aquarium and be regular with water changes and tank maintenance. This is the only way to ensure a healthy environment for your guppies.

I hope you are now better informed about the tank sizes suitable for guppy fish and you will make a good choice for your guppies.

Updated: February 8, 2022
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