Can a betta tank be too big?

I am moving in the next few months and I will have room to create a "fish wall". I have 2 betta fish - well, one is my fiance's but I do most of the care - and I want to upgrade their tanks. The tanks will be blackwater biotopes. I have a 20g long community tank and those fish will be moving along to a bigger tank as well. So I was thinking about getting another 20g long and housing each betta in one of those. But... I'm not opposed to going bigger, either, If I can get approval lol.

Theoretically, can a betta have too BIG of a tank? I know the myth that they do best in smaller tanks is false (one of ours is a juvenile male in a 3 gallon and honestly I feel a little sorry for him, but his upgrade is coming). But can a tank be too big? Mostly I'm wondering if they can be too deep, since they need to surface for air occasionally, which is why I think a 20g long might be a sweet spot for me as they are a relatively shallow tank. What about a 40 gallon breeder tank?

Umm... no. I don’t think there is such thing as “to big of a tank”. A 20g long provides a ton of space for the betta to swim, just like in the wild.

Most people keep them in 5g - 10g tanks because they don’t have the room/money for anything else.

If you have the room/money, I say go for it! (Believe me, I would do that for my bettas if I had a huge house and was a Millionaire! )

I would totally give each of them as big of a tank as you can afford/have room for.

PheonixKingZ said:

Umm... no. I don’t think there is such thing as “to big of a tank”. A 20g long provides a ton of space for the betta to swim, just like in the wild.

Most people keep them in 5g - 10g tanks because they don’t have the room/money for anything else.

If you have the room/money, I say go for it! (Believe me, I would do that for my bettas if I had a huge house and was a Millionaire! )

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FishFinatic77 said:

I would totally give each of them as big of a tank as you can afford/have room for.

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Okay! Another idea that popped into my head was splitting a 75 gallon for them...That might be easier on the budget as it's one tank, one stand, one filter, etc versus 2 of everything, and I could sell my 20g to fund some of it. Hm! I was just worried about it being too deep!

Luckily used tanks crop up all of the time around here, so I can get pretty much whatever I need for a good deal with a little patience.

I have a 20 gallon long and like it better than my 29 gallon tanks. I think that would be great. I bought a tank divider and tried it out and it worked well. I used it on my 55 gallon tank but it will work in my 29 gallon tank too. They may make one that will fit a 20 and you could have a betta on each side.

Big tanks are great just be aware that having a large tank devoted to a betta will really limit any other stocking options, should you choose to go that route

You're right in what you've said, a tank can be too tall for a betta, especially as they grow old, they will indeed struggle to reach the surface for air aswell as feeding. It's been known for bettas to even peck their own fins to shed some weight in order to climb to the top. It's the same preference as keeping a poorly betta in a "hospital tank" with a lower water level to make it easier for them. I would however advise a large tank and heavily plant it (it would look an absolutely fantastic feature)

Your idea of divided a larger tank to house the both of them sounds good also! Best of luck!

Retired Viking said:

I have a 20 gallon long and like it better than my 29 gallon tanks. I think that would be great. I bought a tank divider and tried it out and it worked well. I used it on my 55 gallon tank but it will work in my 29 gallon tank too. They may make one that will fit a 20 and you could have a betta on each side.

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I used to have my current 20 long divided so I do have that divider laying around somewhere, if I decide to keep them in the 20. I agree that I prefer the 20 long over the 29, IMO the 20 long is one of the easiest tanks to maintain because of it's proportions and it is still a decent size if you aren't looking for something massive.

JuiceBox52 said:

Big tanks are great just be aware that having a large tank devoted to a betta will really limit any other stocking options, should you choose to go that route

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Yes, good point! I do have a community tank as well, currently operating in my 20g long which will likely become a 55g corner tank I've had my eye on. I've never been able to choose between a community or a betta...so I have both but I will likely have some otto and shrimp in with my bettas, if they are getting such a large tank.

EllRog said:

You're right in what you've said, a tank can be too tall for a betta, especially as they grow old, they will indeed struggle to reach the surface for air aswell as feeding. It's been known for bettas to even peck their own fins to shed some weight in order to climb to the top. It's the same preference as keeping a poorly betta in a "hospital tank" with a lower water level to make it easier for them. I would however advise a large tank and heavily plant it (it would look an absolutely fantastic feature)

Your idea of divided a larger tank to house the both of them sounds good also! Best of luck!

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You've brought up a great point! The depth of the tank was definitely my biggest concern. My understanding is that naturally, bettas live in expansive but relatively shallow "marshes" so I got the idea that they may not be suite for deeper waters. Perhaps being prepared to move them to a 5 gallon if/when they need it as they age would be a good idea.

squidneh said:

I used to have my current 20 long divided so I do have that divider laying around somewhere, if I decide to keep them in the 20. I agree that I prefer the 20 long over the 29, IMO the 20 long is one of the easiest tanks to maintain because of it's proportions and it is still a decent size if you aren't looking for something massive.




Yes, good point! I do have a community tank as well, currently operating in my 20g long which will likely become a 55g corner tank I've had my eye on. I've never been able to choose between a community or a betta...so I have both but I will likely have some otto and shrimp in with my bettas, if they are getting such a large tank.



You've brought up a great point! The depth of the tank was definitely my biggest concern. My understanding is that naturally, bettas live in expansive but relatively shallow "marshes" so I got the idea that they may not be suite for deeper waters. Perhaps being prepared to move them to a 5 gallon if/when they need it as they age would be a good idea.

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The depth of their natural habitat fluctuates throughout the seasons, theres nothing stopping you from lowering the water level as they age and compensating the loss of water at the top of the tank with something going on above it (I can't remember what aquascapers call that thing when the plants are out the top of the tank and spill over it)
You could grow pothos through floating foam pallets so that the roots drop into the tank and compliment it and the pothos leaves and vines grow out and over the top of the tank. It's an idea I've been thinking about personally for my tanks, although it's more down to your personal taste and how you like to scape your tanks. I dunno, I'm just throwing ideas out there I guess lol. Either way, i hope to see pictures of what you chose to do when its finished, sounds an awesome project, I'm very envious!

A 75g split tank would be super cool.

EllRog said:

The depth of their natural habitat fluctuates throughout the seasons, theres nothing stopping you from lowering the water level as they age and compensating the loss of water at the top of the tank with something going on above it (I can't remember what aquascapers call that thing when the plants are out the top of the tank and spill over it)
You could grow pothos through floating foam pallets so that the roots drop into the tank and compliment it and the pothos leaves and vines grow out and over the top of the tank. It's an idea I've been thinking about personally for my tanks, although it's more down to your personal taste and how you like to scape your tanks. I dunno, I'm just throwing ideas out there I guess lol. Either way, i hope to see pictures of what you chose to do when its finished, sounds an awesome project, I'm very envious!

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That's a pretty cool idea and definitely something I'll be researching more about! I'm moving around December, so I have some time to plan things out. When I do make the move and set up the tank or tanks, I'll certainly make a thread about it!

A betta Biotope tank would look wicked. If you have the time/funds to do so...

I have had bettas for years in various size containers and schemes. About 4 years ago, I had a 2.5gal betta hex tank, but decided to go to 10g,, ended up with 3 bettas in 3 10g tanks, nice little tanks mates (green tertas, khuli loaches, corys snails) ... many of my bettas in the past have lived 5+ years, one was almost 7, in my 2.5g hex - Never had any male betta live much over a year in the 10gs, had a 29g female tank (4 girls) that the oldest lasted 18 months..... I think my boys in the small tank, with a mirror half the time, light on constantly, live plants live food.... they lived the longest and were the strongest One has fin/scale rot, and survived... his pic is attached... he was almost 6 when he passed, living at least a year after he recovered. Rumble Too

Very jealous that you get to have what sounds like a wonderful choice of big tanks, and it's so wonderful that your first thought is to give your current fish the best possible life they can have! I would love to see pictures as well when it's all set up
@Byron has mentioned research before that makes me nervous about divided tanks with shared filtration and water for fish like bettas though, and you might want to consider whether you want to do a divided tank/shared system, or something like two 20 gallon longs next to each other.

I'll see if I can dig up the links or posts Byron made tomorrow, but in a nutshell, fish release pheromones and allomones into the water. So a betta will release certain pheromones, and a prey fish like tetra might release allomones as a result of sensing the betta in the same waters. Have seen a video once of a certain type of sea creature, a stonefish or something maybe? Where they put it's natural predator into tank water, then removed it and placed it's prey in the same water, and the creature freaked out. It could sense the predator though hormones or chemicals or something in the water. They did a side by side of the same creature (I wish I could remember what it was!) going into clean untainted water, and going into a tank where the predator had been in the same water, and the difference was incredible, it reacted so strongly, immediately.

Things like that make me wonder whether bettas can sense another betta that's in the same water. They're so territorial, and the water they live in in the wild is often murky, it would make sense that they also use other senses to detect prey and competition. If they know another better is so close by, but can't see it and deal with it, I can imagine that leading to some chronic stress. For those reasons, I'd choose separate tanks to be on the safe side.

My double tail Beta is in a 5 gallon tank. Having a sole Betta in say a 30 gallon tank or 2 Betas in a divided 75 gallon tank is overkill in my opinion. Betas don't swim very fast and tend to rest a lot. Water changes on my 5 gallon tank are EZ-PZ, taking maybe a total of 5 minutes using Orange Juice containers to remove 2 gallons of water and then refill the tank. No buckets and no Python water changer is needed. A 30 gallon tank would be a waste of water and electricity for a sole beta in my opinion.