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Last update: April 7, 2021

Best betta tank size (The wrong size can kill your fish!)

It’s a hotly debated topic:

What size tank is best for your betta?

If some fish stores and aquarium brands are to be believed, they can be kept in tiny cups or 1-gallon tanks.

Straight up, this is wrong. These tanks are too small.

Today, I’m going to set the record straight.

Want the answer? Read on!

What is the minimum tank size for a betta fish?

Three bettas in jars and tiny tanks that are too small and inhumane

I am often asked…

What is the minimum recommended size for a betta tank?

I dislike this question.

It’s like asking, “What’s the least I can do to keep a fish?”

Imagine if your parents asked, “What’s the least amount of room I can keep a child in?” Before they lock you in a closet.

You should be asking, “What size tank is needed to make a betta happy?”

Today, I’ll answer that.

Online, you often see 2.5 gallons as the minimum recommended-sized tank for a betta.

But don’t run off and buy a 2.5-gallon tank just yet!

You see, a 2.5-gallon tank allows your betta to survive.

But since you are an awesome pet owner, you want your betta to be happy and healthy. You don’t just want your fish to survive, you want them to thrive!

Let’s compare it to yourself. I mean, you could survive in a cupboard, right? It doesn’t mean that you are healthy or happy. To thrive, you need more room than that.

Well, the same goes for your betta.

The ideal sized tank for a betta is 5 gallons or larger for a single male or female betta.

There are a number of reasons why 5 gallons should be the minimum size you consider, some of which are quite technical. To keep things simple, I’m going to give you the most compelling reason to choose a 5-gallon tank…

In a tank smaller than 5 gallons, your betta won’t live out his full life span. In an aquarium, a betta should live for 3 to 5 years. In a cramped 2.5-gallon tank, your betta won’t live as long.[1]

Yes, you read that right – a tank that is too small can lead to an early death.

As a pet owner, your job is to give your betta a full and healthy life. And, you just can’t do that in a tank smaller than 5 gallons.

I know 5 gallons seems like a lot of room, especially when you consider the size of your fish. But let’s compare it to you again. Your home is considerably larger than you are, right? It gives you room to move!

Check out this betta in a 2.5-gallon aquarium…

Half-sun betta in 2.5-gallon tank that is too small

Now, let’s compare that to a 5-gallon one…

Crowntail betta swimming around in 5-gallon tank the right minimum size

So much more room to move, right?

On the flipside, there is no such thing as an aquarium that is too big for a betta. Where possible, a bigger tank is always better. But if you are tight for space, a 5-gallon tank should be the bare minimum you consider.

But as you will soon learn, the amount of water your tank holds is only one step toward choosing the best tank for your betta…

Other factors that affect what size betta tank you should buy

As you might have noticed, there are many different aquariums to choose from. Even if it holds 5 gallons, the tank may not be right for your betta.

Let’s take a look at other things you need to consider when choosing the right tank for your betta…

1. The shape of your tank – not all tanks are equal

If you go to your local pet store, you’ll soon realize that 5-gallon tanks come in all different sizes and shapes. Which one is right for your betta?

Not just any 5-gallon tank will do for your betta.

You see, 5-gallon tanks come in different sizes.

This one, for example, is taller than it is long.

Tall Marineland 5-gallon Portrait Glass LED aquarium wrong shape for betta

These tall tanks are less suited to betta. You see, in their natural environment, bettas live in shallower waters and prefer to swim left and right. A deeper tank actually gives your betta less room to swim naturally.

Here is a 5-gallon tank that is longer than tall…

Long Fluval Spec V 5-gallon aquarium with rosetail betta swimming inside is perfect for betta

If you plan on keeping a betta, this is the type of tank you want – one that is longer than tall.

2. What you place inside your tank – save room for your betta

I think you’ll agree with me when I say…

One of the most fun parts of setting up a betta tank is decorating it!

A quick trip to your local pet store will provide all kinds of funky decorations to put in your tank – my niece loves the one shaped like SpongeBob’s pineapple house.

But the thing to remember is that all these decorations take up space. Small tanks don’t leave a whole lot of room for decorations and your betta.

Here is an example of a betta tank with too many decorations…

An oversized decoration making the right-size tank too small for a betta

While that ornament makes a lovely centerpiece, it doesn’t leave your betta with much room to swim around.

This doesn’t even take into account other betta tank essentials such as filters, heaters, gravel and anything else you try to squeeze into your tank. Remember, it all takes up space!

Check out small aquarium heaters and tiny sponge filters. Their small size will leave more room for your betta.

Remember: If you want to fill your tank with fun decorations, you need to leave enough room for your betta to swim and explore.

3. Choose a tank with a lid – betta can jump!

It might surprise you to learn that betta can leap out of their aquarium. Not realizing that there is no water on the other side of the tank, your adventurous betta may decide to make a break for it.

And when that happens, you could return home to this…

Betta lying on wooden floor after jumping out of tank with no lid

Your betta, lying on your floor.

I don’t need to tell you that fish don’t do too well out of water.

Yep, while your betta might not look like the most athletic of fish, he can quickly turn into a world-class high jumper if he so chooses.

Fortunately, this behavior is easy to fix – buy an aquarium with a lid.

Yep, that’s all it takes to prevent your betta from making a jailbreak.

If it’s too late and you have already purchased a tank for your betta, you can often buy lids separately or even make one yourself.

Bettas that need a larger minimum tank size

Now, there are exceptions to every rule. Let’s take a look at different two betta setups that need a larger tank than 5 gallons…

1. Giant betta tank size

Giant betta floating in a planted 10-gallon tank

10 gallons minimum

Giant betta, sometimes referred to as King betta, are twice the size of your regular betta fish. Because of the difference in size, Giant betta need a little more room – it’s recommended that they be kept in a 10-gallon tank at minimum.

2. Betta sorority tank size

Two female bettas in a 20-gallon planted sorority tank

20 gallons minimum

Unlike male bettas, who will fight with anything that comes close, female bettas can live in groups. This group is called a sorority. A long, 20-gallon tank is the bare minimum and can hold up to 5 female bettas.

FishLab Note: Please note that attempting a betta sorority tank isn’t advisable for beginners because it takes a lot of effort to keep the peace.

What happens if your tank is too small for your betta?

Blue betta fish in a glass jar that is too small

To put it simply, your betta’s home is also his toilet. Poop and pee from your betta will break down into chemicals that will make him sick.

Because there is less water in a small tank, these chemicals build up quickly. Much quicker than they would in a larger tank, leading to serious health problems.

Think of these chemicals as if you are adding a teaspoon of instant coffee to a small cup. The water changes color, and you can taste the difference. However, if you were to add the same teaspoon of instant coffee to a swimming pool, you wouldn’t even know it’s there.

The right-size tank will stop these chemicals from building up as quickly. Ideally, you should be able to go a week between water changes – a 5-gallon aquarium should allow you to do this.

Important: If this is your first betta tank, then check out my guide to cycling your aquarium. This crucial step is often skipped by beginners, who then wonder why their fish are sick and dying.

Best beginner-friendly tanks for betta fish

Straight up, the best time to grab an aquarium is during Petco’s dollar-per-gallon sale. They sell Aqueon open tanks for a dollar per gallon. This special is in-store only, but it means you can pick up a 10-gallon tank for just $10. Just be mindful that you’ll need to buy a lid separately.

If you can’t wait for the next dollar-per-gallon sale to roll around, then here are my favorite beginner-friendly tanks that you can order online, right now.

All my recommendations are glass. Acrylic (plastic) tanks scratch easily – these tiny scratches quickly add up and will soon obstruct your the view of your pretty betta. For more reasons to choose glass, check out our glass vs acrylic tank guide.

1. Fluval Spec V

Fluval Spec V Aquarium Kit 5-gallon white best tank for betta

The Fluval Spec V is a stylish, long aquarium that contains everything you need to give your betta the ultimate home. Well, everything except a heater. But the filter and lighting are included!

At 5 gallons, it’s the recommended size to give your betta plenty of room to comfortably move. Best of all, everything that runs the tank is hidden off to the side – it doesn’t take up room inside your aquarium.

For the heater, grab a Hydor Theo – it’s the most reliable heater that is the correct size to fit in the heater cavity.

For an aquarium kit, this is as good as it gets.

2. Marina 5G LED

Marina 5G LED runner-up beginner aquarium kit for betta tank

Slightly cheaper than my number one recommendation, the Marina 5g LED is a kit that includes everything you need to keep your betta happy, again, except a heater.

The design might not be as sleek as my top pick, but this long tank checks all the boxes in an appropriate-sized betta tank.

3. Aqueon Black 10 gallon

Aqueon Black 10-gallon tank a blank canvas for betta

Finally, we get to my favorite way to set up a betta tank – with a blank canvass.

Don’t let the cheap price fool you. This basic tank is much less beginner-friendly in that you need to purchase all the essentials separately – such as a filter, light and even a lid.

But it really gives you all the freedom you need to create a stunning environment for your betta.

Why do fish stores sell bettas in small cups and vases?

Silver betta with red fins kept in betta cup that is too small

If you walk into your local PetSmart or Petco, you’ll likely notice that they keep their bettas in tiny cups.

Unfortunately, this further spreads the myth that tiny tanks are appropriate for bettas.

Here is the dirty little secret…

Bettas are cheap. You can grab a betta in a cup for less than $5. A betta doesn’t make the pet store much money.

A pet store only has so much shelf space. Instead of using this space to give each betta the right-sized aquarium, they use the space to sell products that make more money.

The end result is that bettas get squeezed into the smallest space possible – a small plastic cup.

It’s an unfortunate part of many pet stores – the animals they sell are seen as disposable products rather than living creatures.

As a fish addict, I visit my local fish stores multiple times a week. I am sad to say there were many times I have seen a dead betta floating belly up in a cup. These cups are just too small to keep a betta healthy and happy.

This is why bettas purchased in cups often become brighter-colored and their fins grow larger when placed in the right-sized aquarium – they are much healthier in a larger aquarium.

I would note that smaller, independent fish stores generally store their bettas in more appropriately sized tanks.

It is for this reason that I suggest supporting your local fish store. The bettas you buy from them are going to be considerably healthier because they come from a larger tank.

Conclusion

Choosing the right-sized tank is the most important choice you’ll ever make for your betta – one that will affect his quality of life.

Whatever you choose, remember…

5 gallons is the minimum tank size for a betta.

Trust me! Your betta will thank you for it.

What tank does your betta call home? Let me know in the comments below!

By Ian Sterling

I've been keeping fish for over 30 years and currently have 4 different aquariums – it's an addiction. I'm here to teach you everything there is to know about fishkeeping.

I also use this site as an excuse to spend lots of money on testing and reviewing different aquarium products! You can find my reviews here.

Comments (65)

Hello Ian
I have built a concrete aquarium outside . It is approximately 40×90 Inches and 46 Inches high . The two sides have a large opening approximately 28×70 for a transparent panel . In your opinion what would the best panel be good for it ?

Respectively Philip

Hi Philip,

Glass as it won’t scratch or yellow in the sun. 150 gallon tanks are around this dimension for panel size.

Hello Ian! I have a betta that I’ve affectionately named dummy. (His first week in his new tank he kept on flaring his gills out at every shadow in his tank. So it seemed appropriate. ) I have him set up in an aqua culture 29 gallon all by himself, with a whisper quiet submerged pump, a low flow bubble curtain for additional air circulation, and a small tank heater. When I picked him up from Walmart 4 years ago, he was the absolute smallest out of all the ones in plastic cups, and the ghostlyst gray blue you’ve ever seen. Here it is 4 years later, hes positively huge, and black and blue. I made sure to swap water weekly so far, and I feed him once a day at 6 PM like clockwork. (Aqueon color enhancing pellets)

Anyway, I have a couple of questions. First question is, what kind of foods would make good extra treats for him? I’ve only ever used the pellet food, never flakes or anything else. I can’t seem to find a solid answer on what’s good for a veiled tail betta for snack type treats.

Second question is, I was considering upgrading to an even larger 50 gallon tank once he hits his 5 year mark, and I’m not sure how he would be with smaller fish to give the tank a bit more life. If he wouldn’t react too well to other fish, would the 50 gallon be too much for him?

Hi Mike,

Fish are not like cats or dogs in that you feed them treats. Fish are perfectly content with their regular feeding – overfeeding causes health problems.

On the tank size, there is no upper limit on how large a tank you can get (in the wild, the amount of water these betta live in could fill the room) just be mindful that the average lifespan of a betta in captivity is typically 3-5 years. I only say this as I have seen people make changes, such as swapping out tanks and then blaming that on why the fish died, when it was simply it’s time to go. At 5 years, your’s is an ooold betta, it shows you are taking great care of him and for that I congratulate you!

Hi! Your site is very helpful so thanks. I have a 20 gal long planted tank that is newly cycled. Zero ammonia, zero nitrites. The nitrate has gone down from 20 ppm to between 5 & 10 ppm this week. (hard to read the actual colors on the API test kit.)

I read online that keeping one Betta is inadvisable because he won’t generate enough waste to keep the biological balance. Is this true? I currently have a small male in a 3.5 kit tank and ready to move him into the 20L.

What about if I add a small snail or two? I read they don’t generate enough waste either.

I had a few danios in there to finish the cycle and returned them to my neighbor when I reached this stage (LOL). NOW I’m worried without live fish it will have to start all over again. OR will the biological material in the canister filter and substrate be enough?

If it matters, I use Prime and Dr. Tim’s bacteria on Fluval Stratum substrate. I used a sponge filter and a great Fluval Nano 10 canister filter during the cycle. I found out about the Fluval Nano 10 (or 30) canister filter which is great for Bettas because the flow can be very gentle. (I got it from a client who needed to move and asked me to take her 3.5 gal with the Nano 10 and juvenile Betta).It has a sponge and ceramic rings with room for carbon which I don’t use.

I also made it an early stage Blackwater tank.

So bottom line, will one Betta keep a tank cycled by himself? (I really don’t want a community tank so much).

Hi Cindy,

The cycling process is all about growing enough bacteria to support whatever you add to your tank. It will then “starve” back to a population that can survive off the waste that is being produced by your fish. Even a single betta produces enough waste to keep a tank cycled. If your ammonia and nitrite read zero, and only your nitrates continue to rise, then everything is normal.

Oh, and in the future I recommend a fishless cycling method, it beats using danios.

Thanks! LOL I know and agree but I was using the former owner’s already cycled gravel, (in bags) and Fluval Nano 10 canister filter with all existing media and an additional sponge filter on the new tank and it was going very smoothly without any drama. Nothing really spiked as you’d expect.

. The Danios weren’t in there from the beginning of the new cycling tank – only the past couple of days when my levels were good at 10 ppm nitrate.

I left out the part that there was a cory and pleco in the 3.5 gallon with the Betta and when I saw my 20L wasn’t really spiking badly at first, I put them in there.

Then I gave them away a few days ago since the owner told me the pleco already went after the Betta and I felt sorry for the Cory being alone.

The Danio thing was a dumb idea that I decided to add to the bio load when I gave the cory and pleco away just to make sure that any additional ammonia was cycling properly.

I knew they were hardy and that’s what happened, I didn’t have any spikes, thankfully.

Thanks!

Your page is so helpfull!! I will probably get my first beta (and proper first fish since as I child I’ve killed so many…).
The beta in the floor was so funny!!

Hi Vero,

Thanks for the feedback 🙂 Welcome back to the hobby. I’m sure you’ll make a great betta parent now that you understand what you are doing. Wishing you all the best!

Hi!! I have a very happy girl Betta named Honey. She’s a Bumblebee Super-Delta long-tailed female Betta runt, so she’s considerably smaller than most females her age…however, he fins are much longer than most girls!! ????

Honey is a 10 month old baby that’s super active, playful, silly, and very playfully “aggressive”! Any time you put your finger up to her tank, she’ll flare the crap out of it ???? She enjoys playing “hide and seek”, “flare at the evil finger”, “dance like crazy”, and other games that she made up herself

Though Honey is already 10 months old and should be fully grown by now, she happily retains the size and looks of a 2 month of female Betta fry. She’s a special girl, and is quite spoiled! ???? You wouldn’t believe what tank she gets all to herself!!

Maybe I’m overdoing it a little or giving her “too much space”, but trust me…she really enjoys it!! ????

I’ve given Honey the mansion of mansions! The king of all Betta tanks! I’ve given Honey a 37 gallon Tall low-tech, heavily-planted natural aquarium! It measures 13″ deep, by 31″ wide, by 22″ tall and is complete with two $40 20 gallon canister filters, a really good $25 heater, a beautiful $45 LED light, a $20 glass hinge-top lid, a beautiful $90 white wooden cabinet stand, and so much more! It’s stocked full of live plants; enough for her to have several “suites”, as I call them ???? The plants also get special care of their own…which is their substrate! The substrate goes at an angle, so the front of the tank may have about 0.75″ of substrate, but the back will have nearly 2″ for optimum plant growth! The bottom layer has 0.5″ of organic black soil going front to back; the middle layer has 0.65-1.4″ of Eco-Complete going at an angle from front to back (I’m sure you can picture it), and the last layer is about 0.1″ of natural play sand so that Honey can have all the fun exploring and searching through the sand for any morsals that have been left behind ???? And best part is, she gets it all to herself!! See, Honey is quite aggressive towards other fish, so she needs to stay alone (or somewhat alone to where she can’t notice the others), so the only inhabitants that are even remotely allowed to share her space are Snails and MAYBE some Shrimp. I’m considering a Nerite Snail, a Black Devil Snail, a Japanese Trapdoor Snail, and maybe a couple Amano, Bamboo, or Ghost Shrimp. She’ll likely also be getting 2 Otocinclus friends soon, but only IF she allows them to be her full-time window cleaners and furniture dusters ????

Overall, Honey has a really happy life, and I honestly think that all people should start keeping their Bettas in oversized tanks! They’re so happy and active and are constantly enjoying their big space! Plus, they’ll thrive and live a long, healthy, happy, and stress-free life…which means they’ll usually live longer! Seriously, do this for your beloved betta friends…you won’t regret it!!

And just a little extra note: The longest-living Betta I had was named Ghast; he was a 6 year old purple, blue, and white combtail who lived pretty much the same way as Honey, but in a 12 gallon acrylic bowfront instead of a standard 37 gal lol…unfortunately, he just recently passed away, but luckily, in return, I now have a little custom-painted canvas picture of him I keep hung in my room at all times!!

Hi JustAFishServant,

Hahaha, you crack me up. That was hilarious, but in a good way. While you have taken things to the extreme, with such a large tank, your betta is likely very happy. Betta typically live for 3-5 years in captivity and Ghast living to 6 shows just how happy he must have been – happy betta live longer.

Wow, you truly do live up to your name. Oversized tanks are beautiful to look at as well, one of the people at my local fish tank has a 50 gallon blackwater tank just for his betta, it looks stunning with all the different seedpots on the bottom – If you have never seen a blackwater tank I advise you to check them out, his betta loves it!

I agree, the bigger your tank the better. Unfortunately, people want to squeeze as many fish as they can manage into a small tank. Your attitude is very refreshing!

Also, I LOVE that you have a canvas picture painted to memorialize Ghast. He truly was a loved fish and I’m sure honey is too.

Thanks so much for sharing this, you made my day!

I don’t agree that “bigger is better”. In the wild, Bettas are born in tiny rice paddies. That is their natural habitat. I had my Betta fish living very healthy and happy for several months in a 2.5 gallon tank. Read about how this was “abuse” so I decided to put him in a 10 gallon. A few weeks later, he was dead. Bettas do not like large tanks. What we think would work for us as humans, doesn’t translate to fish. Yes, we may like a “bigger space” but that doesn’t mean the fish would! They like smaller space- But not too small (like the cups). A 1.5 gallon or 2.5 gallon is a good size for a Betta fish, especially since it is usually kept alone. I think most people in the pet industry like to make $$ by getting people to be over sized tanks for their fish.

Hi Meade,

I don’t really like weighing in on this debate, but you are incorrect here. I’m not sure if you have ever seen a rice paddy, but they are anything but “tiny” and often span for many acres. To put that in comparison, the amount of water would far exceed any tank that is commercially available in the fishkeeping hobby.

I can say with near 100% certainty that it is not the 10 gallon tank that killed your betta and your statement is “bettas do not like large tanks” is incorrect. I would further add that a 10 gallon is not a large tank. If your betta died in the larger tank after just a few weeks, he was either already sick, or something you did accidentally lead to him passing, such as forgetting to cycle the tank.

With that said, I definitely agree with your thoughts on the fish keeping industry pushing products that people do not need. But a larger tank certainly isn’t one of those products.

I wish I read this article sooner. I bought a 2.5 gal tank and a beta fish for my granddaughter. Unfortunately this morning when my son & granddaughter were going to feed it, they couldn’t find the fish. My granddaughter told her father that it was sleeping under a rock but that wasn’t the case. My son found it under the table dead. Even though the tank has a cover with a small opening, we were never told that they could jump. For now we’ll keep the 2.5 tank and take out some of the decorations and try to put some kind of mesh, so that the next fish won’t fly out.

If we don’t buy another beta fish, could you suggest what would be nice and color for my 4 year granddaughter? Thank you!

Hi Mia,

I’m sorry to hear that happened to you. Unfortunately, much of fishkeeping comes down to learning by accident. These things happen and It’s a mistake you won’t make again.

A 2.5 gallon is too small for just about any fish but a single betta, alternatively you could create a shrimp tank with 5-10 shrimp. unfortunately, most fish won’t last long in a tank this size.

I got a new fish yesterday (I already have one, had him for two years and he had been at the pet store for a while).
Anyway, I have 20L tanks (around 5 gallons), and I have pebbles and plants and a filter, and I keep an eye on the temp, but where I live, I don’t need a heater because the temperature in the water is naturally the right temperature.
I filtered the tank for 24hr (with water conditioner and everything), and I brought my new fish home yesterday and I woke up this morning and the water looks kind of murky.
What do I do? Is there something wrong? Or is he just settling?

Hi Tayla,

When you first set up your tank, you need to do a process known as “cycling” Unfortunately, many pet stores such as petsmart or petco will often not tell customers about this very important step.

If you are setting up a new tank, read this guide:

https://fishlab.com/how-to-cycle-aquarium/

If you already have your fish, read this guide:

https://fishlab.com/fish-in-cycle//

On the white murky cloud you are seeing, this is common during cycling and generally goes away before the cycle is complete.

Fantastic article! I HATE walking into pet stores and seeing those bettas living in tiny cups when everyone else gets a big tank! Every time I see one floating in its cup, I die a little inside.

I’m very scared and i’m on the verge on crying, i just got a king beta today, i didn’t do much research on the type of beta before but i asked the “fish expert” if they need different care. She simply said no, its just a koi, at home i already had a 5 gallon tank running and cycled with plants. So i put the beta in ( oc i let the tempiture agust ) and then i did a little more research and i found out the need a 10 gallon at least. But he seems happy and healthy and i’ve been going on to chatrroms and there saying theres is happy and healthy, ( BUT THAT WAS 6 years ago ) plus, i’m broke and don’t have enough money for another 10 gallon, what should i do? please help aswell. Will he die or will he live a happy little life?

Hi Shea,

It sounds like that fish expert gave bad advice – Koi need massive tanks, it’s why they are generally kept in ponds.

You have two options, either try to return him since he was purchased on bad advice or try and raise him and buy a bigger tank in the future. He won’t immediately die in a 10 gallon, especially since it’s likely that this fish has not reached maturity. Do your best, watch the water parameters closely (use a test kit) and he will be okay.

I don’t think they’re talking about the regular pond koi. There is a type of Betta referred as Koi because the colors resemble the Japanese carp, but in reality is just a marbled betta bred to have specific colors, so NO, this does not need to live in a huge tank nor in a pond. LOL
Hope that helps!

Is it cruel to put a Betta (alone) into a properly modified and planted Fluval Spec 5? I often read people saying that 10 gallon is better and 5 is a bit too small. And then I feel guilty about getting into the hobby.

Hi Cody,

In my opinion, 5 gallons is enough, anything more is better, but 5 gallons isn’t “cruel”. You can keep healthy happy betta in a 5 gallon without issue. One of the members of my local fish club has a betta that is going on 9 years old in a Fluval Spec V.

Hi Ian,

My name is Ariel and I have a male betta fish. I’ve had him for a couple months and at first the only tank i could get was a 1 gallon because I’m only 12, and well it’s hard to make money when your 12 but, he is now in a 2.5 gallon tank he is doing much better but, I’m sure he would do even better ina 5 gallon tank. Now that not easy for me to do I had to save up to get a 2.5 not knowing that they need a 5 gallon. So as soon as I can I will save up and get him a 5 gallon.
Thank you for the advice in the article.

Sincerely,
Ariel DeHelian????

Hi Ariel,

You are an amazing individual and it sounds like you are going to give your betta an awesome life. Thanks for looking out for your fish!

My parents just gave me 2 small beta fish in a duel beta fish tank. Since it’s not a 2 and 1/2 gallon tank how often should I replace the water?

Hi Grace,

That’s okay. This is quite common. You may need to perform a water change more than once a week, depending on the size of the tank, how much and how often you feed, your cleaning schedule etc.

Unfortunately, the only way to determine this precisely is to use an aquarium test kit (I recommend the API master test kit, it has everything you need) this is a tool that all fishkeepers use to tell what is happening to the water inside the tank. If the tank is building up waste too quickly, as per the test, you would perform more frequent water changes.

Hey, I have a 1.5 gallon tank with two large plants, a filter and colorful blue gravel for my betta. Is that too small?? And also I’ve had my betta fish(his name is Aspen) for a little over a week and he won’t eat!! Im really scared he’ll die. What should I do??

Hi Claire,

I clearly covered my thoughts on tank size in this article. Did you cycle your tank before you added your fish? If not, that might be the reason for him not eating.

I’ve been wondering lately if my betta fish is lonely, so should I get a tank mate for him? And if so, what sort of animal would that be?? Thx

Hello, I have a male betta fish. I didn’t buy him, he was offered to me. His name is Alberto. Alberto was bought during Christmas 2019 and when he was offered to me, he was in really bad conditions. The bowl Alberto lived in was very small. The water looked dirty and his food was all over the place. It broke my heart, so I took him with me.
Since I never had a pet before, I was really nervous, still am. I had to do a lot of research, but first I went to Petco and bought a tank, I read a 5 gallon tank was good for a betta, but larger is better. Since I live in a small apartment and my room is small as well I just got him a 6.8 gallon glass tank. After that, I did a lot of research and turned out he needed a heater. He was in cold water for a day and I felt bad because of my ignorance in this topic. Next day, I bought him the heater, thermometer and he seemed happy, moved more! Third day, I bought him a plant and some java moss balls.
The problem now is, since I got him spontaneously I didn’t know about the nitrogen cycle. I haven’t gotten the water test kit yet. Also I never know how much food I should give him and I think he was over fed before I got him. His belly is a little swollen so I’m going to not feed him for a day. I don’t know how old he is and he seems to have fin rot from the dirty water he was in. I will treat him, but I have to do more research and get educated. I really do love him, and I’ll feel really bad if Alberto dies.
There’s something else concerning me, he seems to be too small, since I think he was over fed, his upper body looks bigger but not too extreme, stills worries me. His fins are long, but it doesn’t look like other healthy looking betta fins, colorful and spread even thought he looks a lot better than he was in the small bowl. I don’t want him tog te bored so I wonder but exercises I can do with him that doesn’t include food.. and how do I know he pooped? Digested? His water temperature is between 78 and 80 c. I clean his tank everyday. He is with me 4 days already, and I really want to save Alberto, thank you!

Hi Lili,

For feeding, 3 of those micro pellets is likely enough. Betta are very easy to overfeed. I think the biggest thing you need to worry about is cycling your aquarium. Unfortunately, you will need to do a fish-in cycle. I have a guide you can follow here:

https://fishlab.com/fish-in-cycle//

You idiot you say you don’t like 2.5 gallon tanks but the one the guy is holding up on the thumbnail is a 2.5 I know because that is the one my betta uses.Not only that he is still happy and has made like 10 bubble nests within 3 weeks m8. You gotta realize bettas can be happy in a 2.5 gallon tank all the other info I agree with.

Hi Yodas MUM,

Since you opened with insulting me, I don’t think we can have a civilized conversation on this topic.

This article is good. I have 2 bettas but they are all in community tanks with fish like: livebearers, tetras, dwarf gourami, corydoras catfish etc.
That’s what I have with my 2 bettas (in a 40 gallon and a 10 gallon)
I don’t have a betta alone though.
The fluval spec V is expensive though so I wouldn’t go with that.

Hi Tom,

I recommend waiting until the next petco “dollar per gallon” sale. It’s the best place to pick up smaller (typically 10 – 29 gallon) tanks at a budget price.

Hi, I have another dumb question!

A Fluval Flex 15G is 15 gallons and a cube shape with 40cm or 15” on each side. That makes it a little less “long” than a Fluval Spec V.

Do you feel that’s enough space for a Betta to be happy?

Hi Cody,

No such thing as dumb questions! Despite it being narrower, it holds considerably more water and would make an impressive home for your betta.

Hello
My betta fish as been living in a 1.35 gallon aquarium for about 1 year and i want to move him in a bigger space like a 5 gallon tank but I’m afraid he’s going to get stressed or maybe die because he has lived in a small space for a long time What should i do?
– sorry for my bad English

Hi,
Thanks for you article it’s been very helpful.

I am a long way away from even purchasing a fish, I really want to understand what I’m doing before bringing a fish home.

I was wondering, I really love the idea of the one white male Betta in blackwater tank. I think the whole set up is so beautiful. There is a lot I need to learn/ research in regards to tank equipment, plants life, making it bioactive etc, but before I start I have a question about tank size:

I don’t like the idea of housing a fish in a tank that’s smaller than it’s natural habitat. As I understand it there are some fish that reach a limit in terms of tank size, and do not enjoy a space any bigger, are you aware of this limit in regards to bettas?
Would 40 gallons for one male be ok? Too much? Just suitable? Or perhaps 60 gallons?
Or is ‘too big’ not a thing for bettas, and in that case should I be looking for a different species of fish entirely.
Space in my home isn’t really an issue, I just want to make sure when I do get a fish he is getting exactly what he needs rather than what is acceptable.

I’m sorry if any of my question is ignorant, I’m just beginning to look into this subject, already I’ve seen many people buy the fish first then do even the tiniest bit of research, so I’m going to make sure not to do the same.

Thanks again,
Maya

Hi Maya,

There isn’t really an upper limit for betta. Bigger is always better for any fish, since it mimics the amount of water in their natural environment (60 gallons isn’t much compared to a lake or river)

It’s always fun to watch a single male betta explore a large tank, but many owners with larger tanks choose to keep a sorority of females instead, since there is more “action” to focus on when you sit back and watch the tank. It’s a personal choice, but most people choose to use larger tanks for multiple fish.

If you are just starting your research, the most important thing to understand is the nitrogen cycle. You can read more on this here:

https://fishlab.com/how-to-cycle-aquarium/

Thank you for getting back to me- I really don’t want to keep a fish in a tank when I know the next size up would increase their happiness.

So there is no breed of fish that becomes stressed out when placed in a tank too large?

Thanks again,
Maya

Hi Maya,

The short answer is no, unless there is nothing in the tank. For instance, many fish like to hide in decorations or behind plants. If your extra large tank doesn’t have any of these hiding spots then it may lead to stress, but if you are decorating for the species then you should be fine.

Hello, we have a 5 gal tank and having a difficult time getting it to cycle,(had him for 2-3 weeks) we have been battling ammonia and hard water, PH is good. It has been constant at .25ppm, doing water 25% water changes every few days. So we decided to upgrade him to a 13 gal with some live plants. We are cycling the tank before we add him. my concern is the tank to tall? it is 25.88L” x 10W” x 18.25H”. We also got a better heater which keeps the water at 81 degrees. Also replacing most plants with silk ones. thoughts?

Hi I did a lot of research before jumping into betta tanks but in the beginning cycling really stuck out to me and idk why but I kind of got cycling tunnel vision. I figured out everything I’d need to do a fishless cycle in a planted tank, knew bettas needed 5 gal minimum and went ahead and ordered a tank and all the supplies. I ended up ordering a Marineland portrait and THE day after I got it set and planted up, I had doubled down on my betta specific research and realized the tank was a bad choice due to the small footprint. So I definitely messed up.

I kept two rocks at the bottom leaning on each other for a little hidey hole. Have some carpeting plants, a marimo ball, dwarf lily, java fern attached to a small rock, and one other tall background plant. I stuck a decent sized anubias to the side of the wall to serve as a natural layered hammock midway-the top of the tank so the betta can have plenty of resting space the whole way up. I got a betta log as another surface resting area. I also added in some frogbit to float to give the betta a better sense of security. Some of the plants I got as freebies with other planrs and they require more moderate – high light so I went and got two more powerful lights than the stock to compensate.

I’d guess I’m about 2/3 of the way through the cycle based on the test readings I have been getting. The betta is a companion for my 3 y/o to help him sleep at night but I am fully responsible for it minus feedings which I plan to supervise/measure out. I bought safety latches for the lid and modified it by adding a handle to make it easier and safer for both my son and the fish. I have an emergency kit with any medicine the fish may need so that we can be swift with treatment, and am planning in the future to hopefully modify the tank by knocking out the back wall/filter area therefore increasing the footprint.

We went and got a 10 gal at the dollar a gallon sale at petco today but it’s not really in the budget to get everything else needed for that tank right now what with the costs of the other tank. I have extra substrate and should be able to get cuttings from the plants in the 5 gal for that tank though so that’s a start. I can use the leftover substrate too but idk, it’ll be a few months before that one is up and running. The plan is to get the betta once the tank is cycled in the meantime as promised to our 3 y/o, and then eventually move it up to the 10 gal and then make the 5 gal a shrimp habitat or something.

How fast should I look into getting the 10 gallon running? Would it be cruel to keep the betta in the tall 5 gallon for 6 months or so?

Hi Lauren,

Completely understandable, if you are a beginner, cycling is like learning a new language. A quick word on cycling, if you were tricked into buying a filter with “disposable filter cartridges” know that you are throwing out the beneficial bacteria when you replace it, which can stall or even crash the cycle. They are a beginner trap and petsmart and petco are notorious for recommending them so you come back to their store to buy replacements.

I love that you are taking this so seriously. Given the care you have taken with this setup so far (really commend you for your research) your betta will likely be fine for the next few months once this tank has cycled.

Ooooh, I wish you didn’t tell me about the dollar per gallon sale being back on. That’s my kryptonite.

Also, a big THANK YOU for looking after your son’s fish. You have no idea how many parents buy their kid a fish and say “if you keep this alive, we will get you a puppy” – that fish has no chance, and it’s negligent of parents to do that.

Hi Ian,

I have my male betta in a 3.5-gallon tank that’s taller than it is long, so I want to get it in a larger, 5-gallon tank. However, it might be too expensive to change it. What’s the cheapest way to get my fish in a better tank?

From Concerned

Hi Concerned,

PetCo have a doller per gallon sale, where you can pick up tanks dirt cheap. I think one is on right now, otherwise, wait until it rolls around again and buy one then. As long as you are maintaining your tank, your betta will be fine until the upgrade.

If you can’t afford a long 20 gallon tank you shouldn’t own these fish. Whenever I hear someone say, “but, I can’t afford”, or “what is the cheapest”, I know they shouldn’t own another living being.

Hello to everyone…. I have my betta in a 20 gallon aquarium with some neon tetras and cory doras. He seems happy. I know I need to add more plants because I only have one.

Hey Ian,
I have a male Betta in a 10 gallon tank. I’m not sure what kind he is (he’s white and tan and has fairly big fins.) We recent moved him in front of our living room window and I noticed he was hiding in one of his little towers a lot more during the day. I though maybe the sun was bothering him, so I made a panel to go over the back of the tank so he didn’t get any direct sun, but he’s still not very active. Is it possible he’s bored? He has two house things and a larger rock with hidey-holes, as well as two plastic plants and two little moss balls. If he is bored, is there anything I can do to keep him happy? Are there smaller fish or snails that I could introduce to his tank that he wouldn’t act agressively towards?

Thank you in advance,
Raz

Hi Rasmus,

Firstly, you are already doing a great job by giving your betta a roomy 10 gallon tank. As always, the first thing you want to check is the water quality. Use your aquarium test kit (if you don’t have one, I recommend the API master test kit, it’s almost impossible to keep healthy fish without one) and your results should read ammonia- zero nitrite – zero nitrate – a readable measurement and pH should be in the preferred zone and stable.

Hello, i would like to know why betta fish need a large amount of space, i understand if it’s a large amount of bettas or if its a giant betta, but why do normal size bettas need big tanks too? I have a normal size male betta in a 2.5 gallon tank and almost always hes on the top of the tank and only moves to go up & get oxygen from the oxygen bubbles he produces at the very top of the tank. Before i had him i had a female betta fish and she would do that same thing. Betta fish almost never move only rarely, so why get a big tank? i’m not saying to have the fish in a very small space such as a cup but what is the need of having a bigger tank if they almost never move? please get back to me when you can, thank you.

Hi Ammy,

Excellent question. Your betta likely does explore his tank – it’s hard to watch them 24/hours a day. Betta fish certainly do move, and they need this extra space. Also, in a larger tank, waste builds up slower (your bettas home is essentially his bathroom too) so even if you are not on top of cleaning, it’s less likely to impact your bettas health. Think of it as a margin for error.

My male betta is in a 36gallon with bottom feeders. He’s constantly swimming all around, hiding in the sand or sleeping on a plant. He’s all over the place. Back when I kept bettas in 5 gallons they seemed a l less active, 10 gallons I could see the difference in activity. After a 20 gallon I realized the more space the more active. Bettas are smart and learn tricks quickly in larger tanks. Definitely go bigger if you can

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