How Big Should A Betta Fish Tank Be? (7 Factors to Consider)

Wondering how big a betta fish tank should be? This guide is for you!

Thousands of betta fish live miserable lives every year because they are kept in tanks too small for them.

Keepers of these bettas make the ill-conceived decision that captive bettas can live in the same conditions as their wild counterparts.

But the truth is that wild bettas have smaller fins and can therefore live in relatively small freshwater puddles.

Also, unlike the captive bettas, wild bettas have access to water that stretches for miles in rivers, rice paddies, ponds, or marshes.

A fish tank for a single captive betta should be 5 gallons big. However, for your betta to live a happy, healthy life, consider providing him with a 10-gallon tank. The betta tank should have all the trappings that make your betta’s life worth living.

These include clean and well-moderated water, plants, and rocks for decorations and hideouts, and the proper filtration, lighting, and heating equipment.

If you provide the correct size tank that’s correctly set up, your betta’s stress level will remain low, and he will thrive.

betta fish tank

What’s the Best Size for Your Betta Fish?

Betta fish adorn our homes and offices with their exciting personalities and bright colors.

Also known as the Siamese fighting fish, these animals originated from the tropical waters of Cambodia and Thailand.

Bettas in the wild live in shallow freshwater marshes, ponds, rice paddies, and slow-moving rivers. Because these waters are shallow, they are naturally warm.

They provide the optimal conditions for the wild betta to carry out its activities and live a healthy life.

Some bettas in captivity live in misery because they are kept in fishbowls and tanks too small for them. A betta kept in such restricting condition will be lucky to live beyond its 1-year birthday.

So, although your betta fish may look like a tiny animal, it needs a tank large enough to carry out its activities.

How big the betta tank should depend on a number of factors. For example, what’s the type of your betta, and how big is he?

Do you intend to house him with tank mates?

As a general rule, the least size of tank to accommodate a single betta should be 3 gallons. However, this is the bare minimum.

It’s recommended that you house this betta in a 5-gallon tank or, better still, in a 10-gallon one if the space in your home or office permits.

A 5 or 10-gallon tank gives your betta enough space to swim, play, and live an active life. A 10-gallon tank can also house your betta with a few invertebrate tank mates.

If you intend to keep your betta fish with other fish in the same tank, you may have to go bigger than 10 gallons.

The rule of thumb here is that you should expand the tank capacity by 1 gallon for every extra inch of fish you introduce.

Remember, it is better you provide a tank too big for your betta fish than one too small.

7 Factors to Consider for Your Betta Fish Tank

#1 – What’s Your Betta Fish Type?

There are many types of betta fish in the world, each with its unique tail, colors, and patterns.

For example, the Crowntail Betta has a spiky tail, while the Halfmoon Betta has a long one that flares into a half-moon shape.

The Plakat Betta is considered one of the smallest bettas because of its short body and fins.

It’s essential to understand your betta type to determine its accommodation arrangements. Of course, the larger varieties of bettas require larger tanks.

Additionally, some variants of bettas are more active than others. Active bettas require larger tank sizes to swim, play, and zoom around.

#2 – What’s Your Betta Fish Size?

In choosing the right size tank for your betta, the size of the fish does matter. For example, the tiny micro bettas that do not grow to be more than 1 inch in length would be content in a 2.5-gallon tank.

However, the same tank size would be too confining for bettas that grow to 4 inches in length. This betta needs a 5-gallon tank – or a 10-gallon one if you have adequate space in your premises.

#3 – Number of Bettas You Intend to Keep

A single betta will do just fine in a 5 or 10-gallon tank. However, the dynamics dramatically change if you intend to keep more than one betta.

You have to consider that male bettas are quite antagonistic toward each other. They are likely to treat each other as rivals and fight a lot if the space is too confining.

Indeed, it is recommended that you don’t keep two males together. But, if you must, you must provide a larger tank – about 20 gallons.

Also, the tank should have a separator and a lot of hideouts.

Females are easier to accommodate together because they are less aggressive towards each other. Even so, you have to consider the number of females you want to put together in a sorority.

A 10 to 15-gallon tank would suffice for two females.

#4 – What’s Your Budget?

How much you intend to spend on your betta fish very much determines how this animal will live. From food to heating and lighting equipment, the money you allocate determines the quality you provide for your pet.

The same goes for the size of the fish tank. You can expect a quality 5-gallon tank to cost less than a 20-gallon tank of the same quality.

Of course, your betta fish will be happier if you can provide him with a larger tank.

However, if your budget is restrictive, you can start with the smaller tank and upgrade when your financial situation improves.

As long as the tank size you start with is a reasonable accommodation for your betta, you are good to go.

However, never make the mistake of providing your fish with a tank too small for him, unless you want him to live in misery.

#5 – Number of Tank Mates

Being territorial fish, bettas aggressively protect the space they consider theirs. As such, you need to provide a large enough tank if you intend to house your betta with other fish species.

While a single betta will be ok in a 5-gallon tank, it cannot live comfortably with another fish in this tank.

A 20-gallon tank will be ideal if you intend to house your betta with one or two other tank mates.

Housing your betta with invertebrates is less demanding because bettas don’t consider these creatures a threat.

If you intend to house your betta with snails, shrimp, and small, docile fish, a 10-gallon tank would be ok.

Remember, every creature you bring into the betta tank needs enough space to breathe, feed, breed, and carry out its other activities.

#6 – How Big is Your Premises?

Your betta fish tank must be in your home or office. Captive bettas cannot be kept outdoors because of their unique needs.

The betta size tank you decide on will depend on whether you have adequate space on your desk, bookshelf, or any other place you want to put it.

You also need to consider that this tank has special lighting and heating equipment. These ones, too, must be accommodated without messing up your room.

#7 – Type of Tank

While some tanks may look cute and aesthetically appealing, they may not provide the best home for your little friend.

For example, some keepers choose a bowl-shaped aquarium because it looks good on their desks. However, this tank type is too restricting, and the bettas do not enjoy living there.

The best tank type should be rectangular, providing the betta fish with a more fulfilling experience.

Also, you’ll find it easier to clean and maintain rectangular tanks than round ones.

What’s the Minimum Betta Fish Tank Size?

For a Single Betta

Although some betta owners keep their fish in 2.5-gallon tanks, this is considered too restrictive for your betta fish by industry experts.

This is more so if your betta is of the active variety that needs adequate space to move around.

The barest minimum for a betta tank is 3 gallons. However, if you want your betta to live a good life, consider providing him with a 5-gallon tank.

A 5-gallon tank is adequate for your betta to swim, play, and be happy. It also has a low bio-load.

Seasoned betta fish keepers know that a 10-gallon tank is the best for a single betta. With this tank, you’ll provide enough plants and decorations for your pet to have a really good life.

For Two Bettas

A 10-gallon tank is the starting unit for two bettas – a male and a female. This tank provides this couple with enough space to mate and produce young ones.

You should divide the tank into two sections to separate the fish before mating commences.

Otherwise, the male betta may harass and stress the female one too much.

For a Sorority

A number of female bettas can live together in a sorority tank. A 25-gallon tank would comfortably accommodate 4 females.

Have this tank designed with more horizontal length than the vertical one. This is to provide your betta females with enough space to move around.

If you intend to keep 5 or 6 females in the sorority tank, consider a bigger one – such as a 30 or 40-gallon tank.

Of course, the bigger the tank, the more space you need to accommodate it on your premises.

What’s the Maximum Betta Fish Tank Size?

In the wild, bettas have access to miles upon miles of shallow river water to live in. This is where they hunt, breed, raise their young, and spend all their days.

There’s no upper limit to the size of a betta fish tank.

Although they are tiny fish, bettas are not supposed to be kept in small tanks. As such, go as big as you can in tank size.

However, you need to consider that bigger tanks are more demanding. For example, do you have enough space in your home or office to accommodate a really big betta tank?

Can you install the proper lighting, heating, and filtration equipment to keep the conditions in the tank stable?

Apart from providing adequate swimming space for your betta, a large tank has a lower bio-load. You don’t have to change the water as often as you would in a small tank.

A larger tank is preferable for your betta fish if you can afford it and have space for it.

What Are the Best Betta Fish Tanks by Gallon?

How Good is a 2.5-Gallon Tank?

Although experts warn against keeping your betta in a 2.5-gallon tank, you may find yourself in a position where you can’t afford or have room for any other.

Arguably, fish in this tank will fare better than those in cups or a fishbowl.

The Pros

  • Bigger and better than cups and fishbowls
  • Can fit in a relatively small space in your home or office

The Cons

  • Too confining for a betta fish
  • Has a high bio-load
  • Shunned and disregarded by serious betta keepers

How Good is a 5-Gallon Tank?

This is the starting tank size for a single betta. Although some keepers put their bettas in 3-gallon tanks, your fish will do betta in a 5-gallon one.

Ensure that this tank has adequate lighting, filtration, and trappings that create an atmosphere conducive to your little fish friend to thrive.

The Pros

  • It is pretty comfortable for a single fish.
  • A significant improvement from a 2.5 or 3-gallon tank

The Cons

  • Not enough space for highly active or short-finned betta fish
  • Need regular water changes and cleaning

How Good is a 10-Gallon Tank?

This tank size is highly recommended for beginner betta fish keepers. It gives your betta enough space to swim and move around.

Also, it is not too big that you’ll find it hard to maintain.

The best 10-gallon tank is equipped with all the necessary aquarium accessories, such as lighting, filter, and heater.

The Pros

  • Can accommodate various types of bettas
  • Low bio-load
  • Adequate water volume for your betta to lead a happy life
  • Not hard to maintain

The Cons

  • Is pricier than smaller tanks
  • Requires more space in your room

How Good is a 20-Gallon Tank?

This tank is good enough for both the long-tailed and short-tailed betta fish. The more active short-tailed bettas find it particularly accommodating because they can swim around unrestrained.

You can have a wide range of modern and sleek designs with the 20-gallon tank. Also, it comes equipped with the equipment you need to create and monitor the right conditions for your fish.

The Pros

  • Can accommodate active bettas comfortably
  • Suitable size for short-finned bettas
  • Low bio-load
  • Comes in a wide range of stylish designs

The Cons

  • Pricier than smaller tanks
  • Requires relatively more space on your premises

How Good is a 20-Gallon Long Tank?

The 20-gallon long tank is a popular version of the 20-gallon betta fish tank. This tank is designed with more horizontal than vertical length.

The 20-gallon long tank gives you betta fish enough space to swim and move around. However, Bettas do betta in tanks with a broader surface area; they don’t do so well in deep tanks.

The Pros

  • It is ideal for a betta fish with a number of tank mates, mainly invertebrates.
  • Has enough room for all your betta’s activities
  • Low bio-load

The Cons

  • Is quite pricy
  • Takes up a considerably large area of a room

How to Set Up a Betta Fish Tank

Housing your betta fish does not end with purchasing the tank. You need to set up the tank properly, ensuring it meets all the right conditions for your betta fish to be happy.

As a beginner, you should be familiar with the equipment for cleaning and maintaining the tank.

Here’s how to make the fish tank safe and comfortable for your pet betta fish:

Install a Water Heater

In the wild, bettas thrive in shallow waters of rivers and other water bodies of tropical lands. Temperatures in these waters are warm and stay constant throughout the year.

As such, your betta should be kept in a warm tank using a water heater. This is important, considering that bettas suffer a great deal if subjected to temperature fluctuations.

Go for a good-quality water heater that will not let you down.

Install a Water Filter

A good-quality water filter keeps the tank clean by removing waste, debris, and unwanted material from the water.

The size and type of water filter depending on the fish tank size and your pocket. Of course, where the life of your betta fish is concerned, you should never compromise on quality.

Use a Water Conditioner

Water conditioners remove toxins from the betta fish tank. For example, some conditioners neutralize phosphates and nitrates that encourage the growth of harmful organisms, such as the black beard algae.

There are plenty of options for water conditioners in the market. Be sure to use a good-quality one each time you change the tank water.

Tank Size and Shape and the Type of Betta Fish

The choice of tank size largely depends on the type of betta fish you intend to keep. While some bettas are long-finned, others have short fins with stout bodies.

Shorter bettas are known to be more active and require a large tank to meet their needs.

These bettas would feel restrained and confined in a small tank, and may not grow as well as they should unless their conditions are improved.

To understand how the tank size affects a betta’s movement, you should acquaint yourself with the movement of this fish in water.

Your betta fish depends on its caudal fin (fishtail) to move through the water. The caudal fin has the proper shape, structure, and stiffness to propel this animal through the water.

Bettas with small, stiff caudal fins tend to move faster through the water. As a result, they are more active because they swim more efficiently.

Betta fish with extra-large fins are poor swimmers. As a result, they become exhausted more quickly and swim slower than their short-finned counterparts.

The large fins in some betta varieties (such as Veitail) make these fish heavier and sluggish. Also, the extra weight pulls them down, and they are more comfortable swimming at the bottom of the tank.

This tells you that short-tailed betta fish need large water tanks with a broader surface area. This is because they need more space to swim, play, and carry out their activities.

Do Betta Fish Need Surface Air?

Most types of fish have specialized gills that have evolved to work entirely underwater. As a result, such fish have little need for surface air, and hardly come up to the water’s surface.

The betta fish evolved differently. This fish is native to the shallow tropical waters of South East Asia.

As such, betta fish evolved in conditions that provided water, warmth, and surface air. Being in shallow waters, a betta fish always had access to the surface air.

The same conditions must be made available for captive-bred bettas. It will die if your betta fish cannot come up to the water surface for a gulp of air.

Your betta’s gills work best in slow-moving water, where this animal has ready access to the surface air. However, your betta will definitely drown if put in turbulent waters.

For this reason, ensure that the filters you install for the betta tank fit that tank size. Also, it’s better to put your betta in a shallow, long tank than a deep one.

If the betta is made to live at the bottom of a deep tank for too long, it becomes exhausted.

This is because its gills use a lot of energy to compensate for the betta’s undersized swim bladders and oversized fins.

Can Your Betta Live in a Deep Tank?

Your betta fish can live in a deep tank if this tank is well managed. The trick is to ensure that the lower level of the tank is filled with some material so that the fish is pushed closer to the surface.

Betta fish do well as long as they don’t have to swim more than 8 inches deep through the water. This is how this fish has evolved.

In its natural setting, betta fish lives in shallow waters of ponds, marshes, rice paddies, and rivers. This allows the fish to have ease of access to the surface air.

Shallow water also enables this little fellow to keep warm.

Being good jumpers, betta fish will keep jumping to the surface to find air if put in a deep tank.

However, all that jumping can be exhaustive and may leave no room for any other activity. To prevent this from happening to your betta, make surface air more accessible.

You can go for a tank design that uses a number of decorations to fill the bottom. In essence, this tank is meant to be shallower as the bottom part has been taken up by materials.

Remember to use material and fillers friendly to your betta’s way of life. In addition, such materials should not compromise the water quality, temperature, and pH levels.

Frequently Asked Questions (FAQs)

How much space is appropriate for my betta fish?

Your betta fish needs a tank with enough swimming room. As such, you should put cups and fishbowls out of the equation.

Also, ensure that the tank is not too deep because your betta needs to constantly come to the surface for some air.

What’s the best tank size for betta fish?

This depends on a number of factors, such as the betta fish type and whether you intend to house some tank mates.

Generally, the best tank size for your betta fish should be about 5 times the length of the fish. So, if your betta is 3 inches, you need a 15-inch long tank.

It should be about 8 to 15 inches wide.

Are bigger betta fish tanks better than smaller ones?

Betta fish love living in big tanks. The bigger the tank, the better for your fish. Here, the emphasis is on breadth and length and not depth.

Bettas perform better in shallow waters than when forced to swim in deep waters.

Do big bettas need bigger tanks?

Not necessarily. As long as the tank is big enough for one betta, the big betta will settle in quite comfortably.

Fast bettas need larger tanks because they are more active. Conversely, the stout, short-finned bettas are the most active of the lost.

They need lots of water to move around and enjoy their existence.

How many gallons of water does a betta need?

A single betta fish needs about 2 gallons of water. However, emphasis should be laid on the dimensions of the space provided than the amount of water.

This is because bettas like swimming around; space to do so is crucial to them.


Regarding the size of betta fish tanks, bigger is definitely better. Your betta fish will enjoy the extra-large space you provide for him to move around doing his activities.

Unfortunately, not everyone can afford big fish tanks as they are pretty expensive. Also, not everyone has room or space on their premises to accommodate large tanks.

Do not pressure yourself if you don’t have the space or finances to buy one of the fancier, bigger, and more expensive betta fish tanks.

You can start small depending on the number of bettas and other fish species you intend to keep. However, do not compromise on quality.

Aim for a bare minimum of a 5-gallon tank for your betta, as this is good enough to make him feel safe and comfortable.

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