What size tank for a Betta Fish? This is actually one of the most asked questions, when it comes to Betta Fish care. We will answer that question shortly, as well as another 4 actionable steps that are crucial to looking after a Betta Fish.

Sometimes I get really sad when I think about the way that people treat their animals, and especially their fish. Especially their Betta Fish. I really wish, anyone who was having trouble with their fish, could reach out to someone who gives them good advice. Then I wish they would take that advice and use it immediately.

Wishful thinking hey. But at least I can share some truth bombs now, with some actionable steps, and even if I only get to one person who needs help with all or one of issues, so long as they take action and it helps then I’m happy.

What size tank for a Betta fish

A fish is a living soul that needs room to be able to stretch it’s fins and swim. All creators need room to swim and move about. I know the guy or girl at the aquarium store told you, they only need a brick sized tank but this is totally untrue. For starters, the water gets polluted in 24hours because no room for a filter let alone a heater. There is no room for plants or for the fish to move around and explore. It’s logical guys. No excuse. You answer yourself. Pretend you were a Betta fish and we asked you :“What size tank for a Betta Fish”? You’d answer at least 10 gallons, if it were you going to live in it. Please be kind to your animals.

Five Most Common Problems Faced By Betta Owners

Ok so the 5 most common problems faced by Betta owners are these:

1.Maintaining Proper Water Quality (Ammonia Spikes)

2.Improper Tank Setup (Size, Heater, Filter) Asking pet store people, What size tank for a Betta Fish

3.Overfeeding and Diet Management:

4.Preventing Fin Damage and Disease

5.Managing Proper Filtration (Water Flow)

These Problems Occur Because of These Things

1. Maintaining Proper Water Quality (Ammonia Spikes): Owners often struggle with managing toxins, particularly ammonia, which builds up quickly due to overfeeding or inadequate filtration. This frequently leads to dangerous,, stressful “fish-in cycling” where owners must perform daily water changes to prevent illness.
2. Improper Tank Setup (Size, Heater, Filter): Many new owners mistakenly believe bettas can live in small bowls, when they require a minimum of 5 gallons to thrive. I believe 5 gallons is hardly enough and a minimum of 10 gallons is only fair on the fish. A common struggle is providing a heated (76–81°F) and filtered environment, as they are tropical fish that need warm, clean, and still water.
3. Overfeeding and Diet Management: Because bettas are enthusiastic beggars, owners often overfeed them, leading to obesity, bloating, and constipation. A properly sized stomach (about the size of their eye) is hard for many to gauge.
4. Preventing Fin Damage and Disease: Bettas are prone to fin rot and tail biting, often caused by sharp plastic decorations tearing their long fins, or stress from poor water quality.
5. Managing Proper Filtration (Water Flow): While they need a filter, strong currents from standard filters can damage a betta’s delicate fins and tire them out. Finding the right low-flow filter or “baffling” the outflow to create a calm environment is a common challenge. 

Need help to know when your Betta is Struggling?

Common Signs of Struggle:

• Clamped fins: Fins kept tight against the body, indicating stress or illness.
• Lethargy/Hiding: A previously active fish that spends all its time at the bottom.
• Fin Rot: Ragged, torn, or black-edged fins.
• “Glass Surfing”: Pacing back and forth, indicating anxiety. 

Here is how to go from Struggling Betta Fish To On The Way To Health Again

The first thing you need to do straight away is see that you Betta does have his fins clamped and notice he is hiding himself away.

If this is the case we need to do a number of things straight away.

How To Help Your Betta Fish To Help Him Survive

In 2026, betta fish owners continue to face several key challenges as they move away from outdated care myths. The most common struggles involve balancing water chemistry and providing an environment that allows these intelligent fish to thrive rather than just survive. 

• Maintaining Proper Water Temperature: Owners often struggle to keep water consistently between 75°F and 82°F. Since bettas are tropical fish, they require a reliable heater; without one, they become lethargic, their immune systems weaken, and they are prone to fatal stress.
• Managing the Nitrogen Cycle: A frequent struggle for new owners is understanding the “cycling” process, where beneficial bacteria must be established to break down toxic ammonia and nitrites. Failure to properly cycle a tank—often due to misinformation about “instant” setups—frequently leads to ammonia poisoning or chronic fin rot.
• Controlling Filter Flow: Because bettas have delicate, heavy fins, they are easily exhausted by standard aquarium filters. Owners often find their fish “trapped” in corners or struggling against strong currents, requiring them to find gentle sponge filters or use baffles to create the calm water bettas prefer.
• Preventing Overfeeding and Bloat: Bettas are prone to obesity and swim bladder disease because they frequently “beg” for food even when full. Owners often struggle to resist overfeeding, which can lead to bloating or permanent internal damage; many experts recommend a stomach-sized portion (about the size of their eye) twice daily.
• Providing Adequate Space and Enrichment: Transitioning from small bowls to the recommended 5-gallon minimum remains a hurdle. Owners often struggle to balance a spacious environment with enough hiding spots and “entertainment” (like live plants or floating logs) to prevent boredom-induced behaviors like tail biting. 

What you must do now to save your Betta Fish

1. Go out and buy a minimum 10 Gallon Tank: If the ones at the pet store are too expensive get on Facebook Marketplace and look for a cheap tank. Hurry go and buy it.
2. Now you need a slow flow filter and a heater. These are inexpensive. If you can also pick up a small sponge filter as a 2nd filter to run in the tank, would be helpful. You will need more sand for substrate, make sure to rinse it in water before adding to the tank. Buy a piece of driftwood, or use some nice smooth river rocks a couple of easy to grow Anubis and some Java Ferns.
3. Set up you Betta tank. If you had an old filter in the other Betta tank, use it in the new tank. If you bought a new filter, use the old filter media in the new filter. The old filter has hopefully had time to grow brown gunk. That is beneficial bacteria. That is the stuff that turns the old uneaten food, and your Betta fish business from Ammonia, deadly to fish into Nitrite, less poisons, easy to get out of the tank when doing weekly water changes. This is why you do weekly water changes, to get the nitrite out. You don’t clean your filter weekly only monthly. When you do clean it, you only rinse it in a bucket of tank water taken out of the tank during the water change, so you don’t kill the beneficial bacteria.
4. If you kill the beneficial bacteria, for the next 3 weeks about, there is nothing to turn the ammonia into nitrite. The bacteria is the only thing that does. If you have killed it the only way your fish will be safe is to do daily water changes, to remove the ammonia, and reduce feeding, so less build up of ammonia. Try feeding half the normal amount.
5. Feeding normally 2 small pinches twice a day. Small pinches. One is ok also.
6. Monthly filter media clean, only rinse in tank water. when putting water back into the tank make sure to use dechlorinate in the new water.
7. Don’t use plastic plants, only silk or live plants.
8. If you got a second sponge filter, this needs to be cleaned less often again. About every six weeks. Never Ever clean both filters in the same week.

Most Important To Remember if Betta Fish is Not Well

Quickly change half the water. Make sure to use De-chlorinator, and if you can use a product like Seachem Prime, or one mentioned in our post here on cloudy water (which you probably don’t even have) but you still probably have a Ammonia spike, and the products mentioned can block Ammonia for 24 hours.

You probably have an ammonia spike, especially if you cleaned the entire tank and filter only a few days ago. You’ve killed your bacteria and the ammonia is spiking. Quick change that water. Get the ammonia out quick as you can. Half feed and do a 50% water change again tomorrow. Everyday until the filter has the brown gunk growing in it that is the good bacteria.

Saving Your Bettas Life

Hopefully you got there quickly enough to save your Bettas life. If not. You now have learned a lesson that all fish keepers learn early on. If your going to get another Betta, make sure you have the tank as described above running for at least 1 month before you add your new fish.

Also when you buy the tank and ask yourself, What size tank for a Betta Fish? Remeber 10 Gallons. Remember buy second hand to save money, if you need to. Remember take care of and love your pets if you are going to have them.

Adding a Stunning Betta Fish Tank Background

Once you have your Betta Fish tank cycled, been running 4 weeks, and your Betta is happily swimming around in his tank. Now is the perfect time to add a Betta Fish Tank Background, and some decorations for your fish tank. You could try one of these stunning designs, you could create a custom design of your own. Make sure to join our email list so you’ll be kept up to date when our new blog posts and new products come out each month. You also get $10 off your first background for a limited time.

Other Questions You May Want Answered About Your Betta

What size tank is best for a betta fish?

5 Gals minimum which is about 18.9 litres

Can a betta live in a 20 litre tank?

Yes it can however it is much less work on you to have him in a larger tank. Keeping water healthy in larger quantities is easier than in very small amounts.

Do betta fish prefer small or big tanks?

They prefer larger so they can have all the things we mentioned including plants and rocks and filter and heater.

Is 2 gallons enough for a betta?

TOTALLY NO NOT CLOSE TO ENOUGH

Can I have 2 betta fish in 1 tank?

No male Bettas will fight so keep them apart. You can have a female sorority tank, however generally more than 2 fish is better and you need a large tank with a corner of the tank set aside for each fish own territory.

Do bettas need a heater in their tank?

Yes they do. They are tropical fish and need a constant warm temperature.

Why can’t you touch betta fish?

Because you will upset their slime coat.

Can a betta survive without a pump?

Yes but it is not optimal and they won’t survive as long unless you are doing daily water changes and at least have an air stone.

Why does Petco keep betta fish in cups?

Because they don’t have enough single tanks. When you buy the fish they can leave it in the cup for you to carry it home. I think it’s cruel but each to their own.

Best of luck and thanks for reading Sharon.