Best Betta Fish Tank Size (Don’t Make This Mistake)

Size doesn’t always matter. But when choosing your betta’s fish tank, the bigger, the better. Bettas love their space, so anything less than 5 gallons is small for these creatures.

I was more worried about moving my own stuff to make space in my room for the tank than how much room the fish needed when choosing my first fish tank. And my fish didn’t like it one bit. He was less active and had no appetite to match his required diet.

Fish need more room to be stimulated, healthy, and happy. Changing to a larger size tank size did the trick. My fish developed a new personality with more room to swim and play.

Most people always ask for the smallest fish tank, and I’ve been guilty of that too. The better question should be what tank size will make your Betta fish happy! 

And we have all the answers you’re looking for when choosing the right tank for your betta here!

The Best Betta Fish Tank Size

Betta fish are known to be hardy, but that doesn’t mean they don’t enjoy the finer things in life like ample swimming space. 

For Bettas, the minimum tank size you should go for is a 5-gallon fish tank.

You should still consider a larger tank even if you buy a young betta fish from the pet store. If you get a one-gallon tank, you will have to upgrade to a bigger tank soon after you buy your first one. The Betta will eventually grow to their full size and need the extra room that only a larger tank can provide.

To avoid cramping the betta in such a small tank with the heater and filters, you should go for a larger fish tank. It’s also better for your pocket if you start with a 5-gallon tank for a single betta fish.

You can use this table below to determine the tank size you need per betta fish:

Number of Betta FishTank Size
15 Gallons
210-15 Gallons
3-520+ Gallons

Don’t forget that choosing the right tank also depends on your betta. Because Bettas can’t directly communicate (unless you’re secretly the Betta whisperer), you’ll have to monitor their behavior to see what size they prefer. 

You might have to change from a 5-gallon tank to an 8 or 10-gallon tank, but you’ll know once you find the right tank size for your betta.

How Big Can A Betta Fish Grow? 

A betta fish can grow up to 2.5- 3 inches, with a male betta fish growing larger than the female betta fish.

blue and red betta fish

Most people believe a Betta fish only grows in proportion to the size of its tank, but that’s not completely true. They can grow to their maximum size with the right living conditions, specifically in a tank with enough space.

Fish can get frustrated in small tanks without room to turn or swim properly in. Smaller tanks cause betta fish to produce a growth-inhibiting hormone that stunts their growth.  The stunted growth also leads to a weak immune system which exposes them to other fish diseases, shortening their lifespan. 

Larger tanks give your betta enough room to grow to their full size. The additional room is also enough for equipment like heaters to maintain the water temperature and keep the tank healthy.

King Betta Fish

While a 5-gallon tank holds enough water for one male or female betta, we can’t say the same for a giant betta fish. As the name suggests, these fish are larger than the normal betta you find in most aquariums.

king betta fish

Also known as the King betta, these fish can grow to 3-4 inches in size with large bodies and fins. So you’ll need twice the size of a normal tank. A 10-gallon tank is recommended for a giant betta fish. 

In a small tank, the giant betta will be more stressed and depressed due to the lack of space. Stress affects fish the same way it affects most living creatures. You can recognize stress in betta fish swimming erratically and scratching themselves on rocks. 

Factors To Consider when buying a Betta’s fish tank

Pet stores offer various betta fish tanks to keep your betta happy. 

Before taking out your wallet, you need to consider factors other than the tank size to create the ideal habitat for your betta. 

Here are three important factors to consider when getting your first betta fish tank: 

1. The Shape of the Tank

Yes, the tank size is important, but so is the shape of the tank. Unfortunately, plenty of pet stores still recommend small tank sizes for betta fish. That doesn’t mean you have to buy them.

betta fish in small tank

While you can get a 5-gallon tank for your betta, they are available in various designs. Some are tall, and others are wide. 

But what about space? Yes, most beginner aquarists will choose a tank that fits the spot they set aside at home, but you also need to consider your fish’s comfort. Is the shape good enough? 

A wider tank is better than a long tank for these tropical fish because, in their natural habitat, they swim left and right in the shallow waters and slow-moving streams. 

Most importantly, ensure your betta’s tank has a lid. Bettas like showing off their Olympic-like jumping skills, but it can quickly turn fatal!

The last thing you want to find when you get home is your fish lifeless on the floor because you forgot to put the lid back on after feeding them

2. The Type of Tank

You should also know the different types of fish tanks before settling on one for your betta.

Fish tanks are divided into freshwater and marine (saltwater) tanks to suit the specific needs of the fish that inhabit them.

But these tanks can also be divided further into cold water and tropical tanks depending on the temperatures the fish need to survive.

Cold water tanks are for fish that don’t need their water heated. On the other hand, tropical or warm water tanks are for fish that need their water at a certain temperature to survive. Like betta fish.

Tropical fish like Bettas are native to the shallow waters of Thailand, so they require warm waters to live a healthy life in closed environments like aquariums.

They can’t survive in cold water for long. Cold water will weaken the betta’s immune system and affect their general health.

They prefer warm water tanks with temperatures of 75-80 degrees Fahrenheit. You can easily maintain this temperature by installing a heater in the fish tank.

3. What to put in a Betta’s Tank

The fun part of setting up a tank is finding what to put in it. As much as Betta fish love their space, they don’t like too wide spaces. So if you love decorating, this part of the job will be delightful for you!

red betta fish in tank

From decorations to corals and rocks, one trip to the pet store may not be enough to choose everything you want to put in your betta’s tank. 

You can put aquarium plants, rocks, caves, and other artificial decorations in the betta’s tank. One thing you shouldn’t forget is that your betta needs space. Decorations make any tank look beautiful, but your betta must still be able to swim and enjoy the water freely. 

Even a few decorations in such a small tank can take up all the space. Too many decorations also don’t leave room to add water heaters and filters to maintain the tank’s water temperatures. 

Benefits of a Bigger Fish Tank for Your Betta

Bigger is always better when it comes to your Betta fish tank. They’ll be spending most of their lives in that tank, so the least you can do is make it as comfortable as possible. 

There’s no such thing as a tank that is too big for your Betta fish. Here are four reasons why: 

1. Increased Stability

The truth is that fish eat food and poop in the same water. So the water quality is one of the most important aspects of keeping fish.

You shouldn’t be surprised that fish waste causes ammonia build-up in aquariums. 

pink betta fish up close in tank

The build-up of ammonia affects the water quality and is poisonous to your betta. If the water isn’t changed frequently enough, this ammonia build-up is fatal to fish. 

Having a larger fish tank will help dilute the toxic ammonia build-up. Making it less dangerous to the betta’s health and immune system.

If you stick to a smaller tank and frequently change the water, your betta will have to adapt to different water parameters constantly.

This is stressful for any fish, including your betta. And the more your betta is stressed, the easier it is for them to catch an illness. 

The smaller the tank, the more freshwater parameters fluctuate. You will need more maintenance and betta fish care to ensure your pets survive, which can take a lot of fun out of keeping fish.

2. Room for Adding More Fish

Another benefit of a large tank is it makes it easier to add more fish. If you are already familiar with the betta’s tank setup and equipment, adding another tank mate will be easier. 

You can’t fit two betta fish in a small 5-gallon tank. Trying will only make them unhappy and irritated.

two betta fish side by side in fish tank

Male bettas don’t play well together, but that’s not the case for female bettas. The latter do well in groups. Like in college, a group of these female species is known as a sorority. You can even keep 5 female bettas in the same fish tank without worrying about a fight breaking out. 

As fun as it sounds to care for a betta sorority tank, it’s difficult for most people because they are still territorial fish.

Starting with one or two bettas is more manageable in the long run if you’re a beginner. 

3. Improved Behavior and Lifespan

Most importantly, you want a bigger tank for your fish to live longer.

But how long do betta fish live? A normal betta has a lifespan of 3-5 years, depending on their living conditions and diet. A lot of factors can shorten their lifespan, including living their lives in a small tank.

To avoid saying goodbye too early, get your betta a tank that has ample space and room for them to grow. 

If you have a betta in a tank with other fish, you’ve probably noticed they aren’t the friendliest fish species. They must have been throwing some good punches to be nicknamed the ‘Siamese fighting fish’, right?

Bettas are territorial, even with their kind. But with enough space to live their best lives, your betta can better deal with other tank mates.

Bettas are known to depict aggressive behavior when kept in small spaces with too many fish. The stress this causes can reduce their chances of having a healthy and long life.

So what’s the best betta fish tank size? 

Bettas are used to spacious and planted areas in their natural habitat. They are the playful kind of fish who like to play hide and seek during their free time. So a tank with plants and tons of hiding places will be the closest thing to their natural habitat you can create. 

The ideal tank size for one betta is a 5-10 gallon tank. But this is only the minimum size to offer your betta fish a happy life. Big is always better if you want to give your pet the comfort they need.

If you have your betta in a small container, it’s probably time to move them into a more comfortable environment before their health is affected.

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