How Big Should A Betta Fish Tank Be (For optimal health)

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When it comes to keeping a Betta fish, one of the most common questions people have is how big should a betta fish tank be. The size of the tank will depend on several factors, including how many fish you plan to keep and how much space you have.

A betta fish tank should have a capacity of 10 gallons or larger. It’s a common misconception that betta fish are happy living in tiny spaces such as small bowls or vases and they have become a popular decorative pet in many homes. Small spaces lead to stress, and poor health, reducing a bettas lifespan.

How Big Should A Betta Fish Tank Be

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If you are looking to set up a betta tank, there are many things to consider, with tank size at the top of the list. So let’s delve a little deeper and answer the question, how big should a betta fish tank be, and why?

What Is The Minimum Tank Size For Betta Fish

A 3 gallon betta tank is the minimum you should consider buying for a single betta fish. 3 gallons will provide enough room to swim, and you will have room for a filter and heater.

Betta fish can live in smaller tanks, but they are not ideal. Small tanks often do not have enough room for a filter and heater, leading to poor water quality and fluctuating water temperatures.

It is also important to note that small tanks tend to be more difficult to maintain as they can quickly swing from one extreme to the other. Ammonia and nitrite levels can rise rapidly in small tanks, which can be very dangerous for your fish. You will need to be careful how often you feed your betta and how much, to monitor waste levels.

The myth that betta fish live in small spaces is due to a misunderstanding about their natural habitat, so what has started this unhealthy trend?

You can read more about a betta’s natural habitat here: Betta Fish Care Guide And Species Overview For Beginners.

A Bettas Natural Habitat

You can find betta fish in many parts of Southeast Asia, often in the rice fields that are plagued with dry weather in the warmer months and flooding during the rainy months.

When the rice fields are flooded, the betta fish can move freely through a large expanse of water, however, the dry season will reduce this large body of water into small puddles, where the misunderstanding starts.

The assumption that betta fish will live in these small puddles for many months has sparked the trend of keeping bettas fish in small ornamental vases and tiny tanks. Still, these puddles are not entirely disconnected, allowing the betta to swim from smaller puddles to larger puddles.

Betta fish are also quite unusual as they can breathe out of the water through a unique organ known as the labyrinth organ, which acts like a human lung. This unique ability allows betta fish to jump and wriggle across the land until they find a more extensive water source.

How Much Room Does A Betta Fish Need

How much room a betta fish needs depends on the tank setup. If you plan to house your betta with other fish, you will need at least a 10 gallon tank. If you plan to keep your betta by itself, a 3 gallon tank will be fine, but a 5 gallon tank would be better.

Betta fish are mostly sedentary creatures and do not require a lot of space to swim. You will often find your betta fish hiding so you should provide plenty of plants and other hiding places to help them feel secure.

What Kind Of Tank Does A Betta Fish Need

Although betta fish don’t need lots of space, they are curious creatures and will explore their surroundings, so a larger tank will provide more room for your fish to swim and explore.

Betta fish typically prefer shorter, wider tanks that provide the necessary room to swim. Betta fish a very territorial, so the larger the perceived space, the easier it will be to find its territory. A taller betta fish tank will feel relatively confined with less room to swim.

Betta fish are also happier in short tanks, similar to the natural environment in which they are found.

What Happens If Your Tank Is Too Small For Your Betta Fish

A tank that is too small for your betta fish can cause several problems. Poor water quality is the most common problem associated with small tanks. Your betta water should be clean and at its best or you risk a multitude of problems occurring.

As betta fish produce waste, the ammonia levels in the water will rise, which can be very dangerous for your fish. Ammonia poisoning can cause serious health problems such as lethargy, loss of appetite, and even death.

Do Bettas Like Small Tanks
Do Bettas Like Small Tanks

Beneficial bacteria will usually control ammonia by feeding on it and converting it into less harmful nitrates. If the tank is small, the waste produced by your betta fish could far outweigh the number of beneficial bacteria that the tank can hold.

Other problems that can occur if your tank is too small for your betta fish are:

It is much harder to maintain any level of consistency in a smaller tank as small bodies of water will fluctuate quickly in water quality and temperature.

One example of temperature is comparing a cup of coffee to a water tank. A cup of coffee, when left to sit, will become cold quickly, whereas a large water tank of heated water will remain warm for almost a day.

If you have a betta tank heater, this is not necessarily a problem as the water will heat quickly, but you should always have a spare heater in case of malfunction and check the water temperature often.

Small tanks often don’t have room for filters, and a lack of filtration will cause rapid fluctuations in water quality requiring regular testing and water changes. You can find out here: How often to change betta water, and also, How to clean a betta fish tank.

Smaller tanks also contain less dissolved oxygen which will cause your betta to sit near the top of the tank to breathe from the air. Although betta fish have this ability, it is not a good long-term solution as your betta will become stressed over time.

Small tanks are generally more stressful for your betta fish as they like to have their territory and space to hide from perceived threats. Even if your betta is the only fish in the tank, it may still feel restricted because they do like to get some exercise.

Stress is also a leading cause of many illnesses such as fin rot, however, a smaller tank will allow other diseases and parasites to develop more quickly due to the difficulty of maintaining water conditions.

Below is a list of illnesses and conditions that you need to look out for:

Although you can find these illnesses in a larger aquarium, the stress of a tiny tank can lead to a weak immune system and a more severe illness.

Everything I have listed, from low oxygen to stress can also impact a bettas growth. For a betta to grow to full size, it will need the best water conditions and little, or no stress.

Juvenile betta fish will also release a growth-inhibiting hormone which is intended to stop other betta fish from growing too big but in a small tank, your betta will be affected by its own growth-inhibiting hormones.

Why Are Large Tanks Better Than Small Tanks

If you are stuck between choosing a large tank or a small tank, you should be pleased to know that there are many benefits to owning a large tank with very few pitfalls.

Large tanks are much easier to maintain than small tanks for several reasons, such as:

  • More stable water quality
  • Easier to keep warm
  • Better filtration
  • More oxygen in the water
  • Less stress for your fish

A larger tank will have a more stable water quality as there is more water to dilute any waste produced. The larger the tank, the less often you need to do water changes.

Tropical fish need a heater to keep warm, and the water temperature will remain more stable in a larger tank, requiring less energy to heat over time. If your heater fails, you have more options to keep the water heated to a suitable temperature until you can replace it.

Another benefit of a larger betta tank is the extra room for a good filter. A filter will keep water parameters much more stable, and the tank will require fewer water changes.

Larger tanks will generally have a larger surface area to help oxygen saturate into the water efficiently. A filter, as mentioned above, will also provide surface water agitation and help oxygen enter the water.

Why are large tanks better than small tanks
Why are large tanks better than small tanks?

A final benefit of having a large betta tank is the added room for your betta fish to swim freely, and you will be able to decorate it with live plants and ornaments, which will make your betta happy. Live plants will positively impact your fish tank’s overall health and will provide places for your betta to hide out, which ornaments will also offer.

In short, the bigger your tank, the better it will be for you and your betta fish. So, how big of a tank does a betta fish need?

What Is The Best Tank Size For Betta Fish

So far, we have looked at the minimum betta fish tank size and the benefits of large tanks over small tanks, but the ultimate question, which I’m sure that many of you are waiting for the answer is, “what is the best tank size for betta fish?

A 20 gallon tank is an ideal betta fish tank size and provides enough room for a few small, compatible tank mates. Although 20 gallons is suitable, if you have room for a bigger tank, then go bigger. When it comes to tank size, bigger tanks are always better.

I have covered a multitude of tank sizes already, with the benefits and drawbacks of each, but many retailers stock a variety of tank sizes from large to very small.

Although I can offer advice, it is not for me to tell you what size tank to get for your betta fish, so I will look at some specific sizes below and briefly discuss the benefits and drawbacks of each.

Below is a useful video that I found on Youtube that shares many of my thoughts on choosing the right betta tank size.

Choosing The Right Tank Size For Your Betta Fish

1 Gallon Betta Tank

Although people go even smaller, 1 gallon betta tanks have become quite popular. Many 1 gallon fish tanks are available to buy with variations that can house several bettas at once.

These smaller 1 gallon betta tanks are often built for quirkiness and can look great in small spaces, which is ideal if you don’t have enough room for a large tank.

Despite their unusual designs and their small space requirements, in my opinion, such a small tank will not allow your betta to enjoy a long and healthy life and is instead an excellent way to display your betta fish in the home without the work required to maintain a larger tank.

How Long Do Betta Fish Live In A 1 Gallon Tank

Betta fish can live for over 5 years in a suitably sized tank, however, if you keep your betta confined in a 1 gallon tank, it may only survive 2-3 years. I say survive because they are not really living the life that has been intended for them.

If you do want a 1 gallon tank for your betta, I recommend having a separate larger tank that you can transfer them into from time to time. I know some people who use small ornamental tanks throughout the day and have a night-time tank.

Alternatively, you can use such a small tank for tiny fish or small shrimp, like ghost shrimp. Small fish won’t need as much swimming space and will not produce the same amount of waste as larger tropical fish can produce.

2 Gallon Betta Tank

My thoughts on a 2 gallon betta tank are similar to that of a 1 gallon tank above. 2 gallons is approximately 7.5 liters which isn’t terrible and will provide some room to swim, but the tank itself will be challenging to maintain.

The water parameters in a 2 gallon betta tank will need regular testing, and you will need to keep the tank away from draughts or direct sunlight to keep the water temperature stable.

Many 2 gallon betta tanks are aimed at beginners or are designed to look good on a small shelf or desk. They are not usually as functional compared to a larger betta tank, with little space for a filter, a heater, or ornaments.

Some beginner tanks may have filtration and heating built into the tank housing, which would be beneficial.

3 Gallon Betta Tank

In my opinion, a 3 gallon betta tank is the minimum size that you should aim for when keeping a betta fish.

Ideally, choose a broader tank to help oxygen saturate the water and provide more swimming space. Wider tanks are also easier to decorate with plants and ornaments, which will give your betta somewhere to hide.

There are plenty of options when buying a betta fish tank in this size range, and many come as a complete aquarium kit that will be perfect as your first betta tank.

If you can find a tank that has a heater and filter built into the housing, it will provide even more swimming space in the tank.

5 Gallon Betta Tank

Like the 3 gallon tank above, a 5 gallon betta fish tank is a popular choice among people with a little more room and will provide almost double the swimming space. Although 5 gallons is not a big tank, your betta fish will feel quite comfortable in a tank of this size, and it should be easier to maintain than the smallest variants.

If you want to keep more fish with your betta, it will not be very suitable, even for tiny fish like tetras. Too many fish in such a small tank can quickly play havoc with your water parameters, so it’s always best to over filter and understock your tank.

You can add plenty of plants and some ornaments to this small aquarium which will undoubtedly make it look the part wherever you choose to place it. The plants will help bring natural bioactivity, meaning more oxygen, more beneficial bacteria, and more stable water parameters.

Once a tank can create some level of bioactivity, specific processes will occur naturally, reducing the need for daily and sometimes even weekly water changes.

10 Gallon Betta Tank

A 10 gallon betta fish tank is becoming increasingly popular with more experienced hobbyists as it provides an excellent middle ground for size, price, and maintenance.

10 gallons will give your betta plenty of space to swim around in, and if you add some plants and ornaments, it will look impressive.

While a 10 gallon tank is not a large aquarium, it’s still 2-3 times the size of a standard betta fish bowl which makes all the difference. If you choose to add other fish to your tank, do your research first, as some fish are incompatible with bettas.

Male betta fish are not compatible with other male betta fish and should only be kept with female betta fish when you are looking to breed them. Because of the territorial nature of betta fish, they will likely become aggressive and want to fight each other.

You should not place larger fish such as cichlids, gouramis, and goldfish with bettas as they will often show aggression and invade your betta’s space, and 10 gallons is also not suitable for larger fish of this size.

As with all aquariums, the larger the tank, the easier it is to maintain. There’s more water to dilute any ammonia spikes and more space for beneficial bacteria to colonize.

20 Gallon Betta Tank

If you are keen to start fish-keeping as a full-time hobby and looking to buy a new tank, 20 gallons is the way to go. A bigger tank will give you plenty of scope for fish choice and aquascaping, and if you are considering keeping other fish in the tank, there will be plenty of room for your betta to hide away if it feels threatened.

Bigger tanks are much easier to maintain, and although a 20 gallon tank may be considered medium in size, it is still much bigger than a standard betta fishbowl, and it will show in the quality of your water.

With a 20 gallon tank, you have plenty of options for stocking, and you can even add some larger fish such as loaches and plecos.

As long as you do your research and make sure the fish are compatible, a 20 gallon tank can be a great way to get into fish keeping, and it will provide years of enjoyment.

Betta Sorority Tank Size

Although you should not keep male bettas together, it is possible to keep small groups of female betta fish together, which is called a betta sorority tank. Betta sororities can be challenging, but if you have a group of female betta fish that get along, it can be quite rewarding and is ideal for breeders.

Female betta fish are not as territorial as their male counterparts, but they will need their own space, with plenty of plants and other decor to separate them. The minimum tank size for a betta sorority depends on the sorority size. A 20 gallon tank can successfully house 3 to 5 female betta fish, however, a bigger tank will increase your chances of success.

Best Betta Fish Tanks (Beginner Friendly)

If you want to buy a betta fish tank, the choice can be pretty overwhelming. Because of the popularity of betta fish, many manufacturers now make tanks specifically designed for them. Many pet stores will stock a wide variety of these tanks, and they are often the popular choice for beginners.

Despite being designed for betta fish, some manufacturers don’t consider the ethical size requirements or the general function of the tanks they put on sale, so you will often find yourself with a great-looking tank with minimal benefit.

When choosing a tank for your betta fish, I suggest looking around and comparing functionality. Ensure that there is suitable heating, lighting, and filtering, which you can easily replace should they malfunction.

Providing good betta fish care starts with your choice of tank, so don’t be sucked in by a tank just because it has been labeled as a betta fish tank when there may be other more suitable and cheaper tanks available.

Because I understand the difficulties when shopping for your first betta tank, I have provided a list below of my favorite choices. The listed tanks vary in size but are the best betta fish tanks that I have had experience with and are suitable for new and experienced fish keepers.

Also, if you are worried that your betta fish may get lonely or bored by itself and feel you need to get a larger tank to add more fish, have a quick read of the article: Do Betta Fish Get Lonely Or Bored On Their Own?

BiOrb Classic 8 Gallon Led Aquarium

BiOrb Clasic - 8 Gallon Led Aquarium
BiOrb Clasic – 8 Gallon Led Aquarium

GloFish 5 Gallon Aquarium Kit

GloFish - 5 Gallon Aquarium Kit
GloFish – 5 Gallon Aquarium Kit

Coralife BioCube 32 Gallon Aquarium

Coralife Biocube Aquarium - 32 Gallon
Coralife Biocube Aquarium – 32 Gallon

Fluval Edge 12 Gallon Aquarium

Fluval Edge 2.0 Aquarium
Fluval Edge 2.0 Aquarium

Marina Led Beginner Aquarium Kit – 20 Gallon

Marina Led Beginner Aquarium - 20 Gallon
Marina Led Beginner Aquarium – 20 Gallon

All of the aquariums listed above are complete kits and would be the best option for beginner aquarists to set up. They should provide most of the equipment that you will need such as internal filters and heaters and you may find that some will add gravel to the kit.


I hope this article has provided you with enough information on how big a betta fish tank should be. If you are considering keeping betta fish or looking to upgrade your current tank, I would highly recommend a 20 gallon tank or bigger, which will give you plenty of space to add other fish, and it will make maintenance much easier.

The absolute minimum size tank should be 3 gallons if you want your betta to remain healthy, live longer, and have a happy life.

Frequently Asked Questions

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Jon O'Connell

I have kept both marine and freshwater fish and set up almost 100 aquariums. Although I am no longer doing it professionally, I hope I can help others to enjoy keeping happy, healthy fish by sharing my many years of experience.

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