Two of the most popular fish to start an aquarium with – even a tiny one – have to be betta fish and goldfish.
Available pretty much anywhere and everywhere aquarium supplies are found, and about as affordable as can be – not to mention super simple and straightforward to care for (for the most part) – you really can’t go wrong starting your aquarium journey with either one of these fish.
Some folks, though, like to “double up” in their first bowl or tank and want to know whether or not it’s a good idea to add these two fish into the same enclosure with one another.
Can betta fish live with goldfish or is that a nightmare scenario just waiting to happen?
We can tell you pretty definitively that it’s a good idea to keep these two fish separate as much as possible. Though they share a lot of traits – similar personalities, similar hardiness, etc. – they just don’t seem to get along well with one another.
They also require different environments to thrive, too. Let’s dig a little deeper into the ins and outs of why betta fish and goldfish shouldn’t be mixed together.
Can Betta Fish Live with Goldfish?
There are a bunch of different reasons you’re going to want to avoid keeping a betta fish in with your goldfish, but the biggest reason of them all has to be the different water conditions (especially water temperatures) that these fish require.
Goldfish need water temperatures that are considerably lower than the safe temperatures for betta fish, but they don’t need water to be quite as crystal-clear or perfectly clean to thrive.
Goldfish (believe it or not) are particularly “dirty” fish and that’s a big part of why they don’t do well with other fish roommates.
Betta fish, the other hand, require warmer temperatures to do well in and also need water conditions that are almost squeaky clean.
They can do really well in tiny amounts of water (they often are stored at fish supply stores in tiny little plastic containers, something you’ll never see a goldfish and), too.
No, it’s a good idea to keep your betta fish and your goldfish separate from one another.
Why Are Bettas and Goldfish Such Bad Tank Mates?
Okay, now that we’ve squared away (at a high level) a couple of the reasons you’ll want to think about keeping betta fish and goldfish separate let’s get into the more “nuts and bolts” differences between these fish, the environments they require, and their temperament – amongst other things – to back up why you’ll want to keep them apart.
1. Tank Size
As we alluded to a moment ago, goldfish really do well in tanks that have a lot of extra room to roam and, so to speak.
Goldfish (even “common” goldfish) can grow to be 12 inches in length or even longer, so long as they have room to stretch out. You’ll want to give them at least 30 gallons with, and 12 gallons extra for every other goldfish you drop in the enclosure.
Betta fish, on the other hand, can get away with tanks that are as small as 5 gallons. Those tiny little Tupperware they get sold in should be upgraded as soon as you get home, and not just to a little “goldfish bowl”, either.
2. Water Temperature
Water temperature really is the main factor you’ll want to be sure that you never mix betta fish and goldfish together.
Betta fish require a very warm water environment as a true tropical fish. We are talking water temperatures of between 76°F and 82°F (though slightly colder or warmer – a couple of degrees, anyway – isn’t the end of the world).
Goldfish, though, are just about a cold water fish in comparison.
These fish like temperatures much lower, between 68°F and 72°F. You might be able to bump water temps for goldfish up to 74°F, but even that is starting to get kind of risky.
Water temperature conditions for these kind of fish – both betta and goldfish – aren’t just suggestions, either.
As soon as temperatures start to get down around 75°F or so your betta fish is really going to start to struggle. Below that serious damage can be done, enough damage that kills your fish in just a couple of days (if not even faster).
Goldfish aren’t going to handle warmer temperatures, either.
Temperature shock sets and almost straight away, jacking their metabolism through the roof and causing a lot of stress, and it doesn’t take long for illness or disease – or even death for your goldfish – to set in shortly after that.
Don’t fool around with water temperatures. Don’t try to meet in the middle at 75°F, either.
Keep these fish apart and in separate enclosures that have water temperatures (and conditions) specifically set to their needs. You’ll end up with much happier fish, easier tank maintenance, and will be able to keep these two kinds of fish – just not in the same enclosure!
3. Ammonia Levels
Betta fish like to have a really clean environment, with water that is almost perfectly balanced as far as nitrogen and ammonia are concerned (amongst other things).
In fact, your betta fish wants there to be as little ammonia in the tank as humanly possible. The more ammonia they have to deal with the more stress they are going to be put through. And it doesn’t take a lot to stress these tiny little creatures to the point of death.
Goldfish, on the other hand, are sort of like the swine of the underwater world.
They might not look at the surface, but these fish are notorious for being very dirty. They release a lot of waste, they pump a lot of toxins out in that waste, and they produce a tremendous amount of ammonia on a day-to-day basis.
The same levels of ammonia that would kill a betta fish in just a few days won’t ever even come close to harming a goldfish. Put them in the same water, though, and it’s not going to take long for your betta to succumb to ammonia poisoning – even as your goldfish flits and flips around underwater.
Don’t mix these fish. You’ll end up wreaking havoc on the health of your betta fish, probably without even noticing just how bad thing are getting until it’s too late to revive those beautiful little creatures.
5. Food Sources
Betta fish eat a relatively strict diet (at least as far as commercial fish food is concerned), and they really aren’t going to be interested in eating anything that isn’t regularly on their menu.
Goldfish, on the other hand, eat pretty much anything and everything they come across – and that includes the fish food that you would have specifically added into your tank for your betta fish.
Super opportunistic, goldfish would have gobbled up that food as soon as it was dumped into the tank. They would have robbed your betta fish of their meals, starving them out while continuing to eat anything and everything you put in the tank for them as well.
This would cause a cascade of different problems, negatively impacting both your goldfish as well as your betta fish.
On the one hand, your betta would be starved almost completely. They aren’t going to last very long once that’s started to happen.
On the other hand, though, your goldfish would have been eating far too much. That’s going to screw around with their metabolism, but it’s also going to put a ton of stress on their bodies and force them to produce a whole lot more waste.
The end result is more ammonia in the water (poisoning your starved betta fish) and chunky goldfish that struggle to swim, start to slow down, and then begin to starve and die themselves.
That’s not a pretty picture. It’s really a good idea to avoid even experimenting with these two fish in the same enclosure, even just for a short while.
It’s not worth it.
While every individual fish has their own unique personality (for the most part) betta fish are known to be very aggressive, especially when they are dropped in a tank with other fish around their size.
Most folks know that the last thing in the world you want to do is have multiple betta fish in the same tank just because of how cranked up their aggression can get.
And while betta fish can do well with larger fish they can’t bully around (provided that those fish also do well in the same kind of tank conditions), goldfish are about the same size – when they are young, anyway – and are pretty aggressive on their own.
No, we’re not suggesting that goldfish are quite as territorial or as “mean” as betta fish can get.
But goldfish are known to be little nippers that like to mouth and bite the tails and fins of other fish. That’s not the kind of behavior that even the most passive betta fish is going to tolerate for very long.
All of a sudden you’ll have a fight on your hands, a fight that you are going to have an almost impossible time breaking up. The only thing a lot of tank owners can do (if they’re even there to see the fight when it happens) is wait to find out who wins – if anyone.
At the end of the day, most of the time these fights are pretty poorly for both of the fish involved.
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A lot of people are tempted to combine beautiful betta fish with the cool, gorgeous goldfish that they are having a tough time picking between when they want to start an aquarium.
That’s about the worst thing in the world you could do, though.
Like we talked about earlier, there are a multitude of different reasons that you don’t want to be mixing these two types of fish.
The water conditions that both of these fish need are wildly different from one another. And since there’s no way to build different water ecosystems in a single tank you’re going to be dooming one of these fish to an early grave the moment that you mix them together.
Combine that with the fact that these fish need different tank sizes (goldfish need a lot more room than betta fish), that they eat different things (and goldfish will starve a betta by eating all its food first), and just don’t have personalities that jive with one another and keeping them separate becomes a no-brainer.
There’s nothing wrong with having a goldfish and a betta fish that you take care of at the same time.
Just be sure that both of those fish are kept separately from one another at all times, in a tank environment dialed in to support them perfectly.
Frequently Asked Questions
Can you keep bettas and goldfish together?
Absolutely not! The absolute worst thing you could do is decide to mix your betta fish and goldfish together for a number of reasons.
Water temperature issues, water condition issues, the dirtiness and cleanliness of goldfish and betta fish (respectively), and even the personality of these fish just don’t mesh well together.
Is it worth the hassle of mixing these two fish?
Some people have still decided to experiment with betta fish and goldfish in the same enclosure, particularly those with a lot of extra space so that these fish don’t have to have a lot of interaction with each other.
Even then, though, the amount of maintenance, direct feeding, and “babysitting” you have to do often makes it more of a headache than it’s worth.
Will bettas and goldfish even get along?
Every single fish under the sun has their own unique personality, but (as a general rule) betta fish are particularly aggressive and territorial with other fish and goldfish are known to bite and nip at the bodies of other fish in their enclosure.
Combine those two things together and you have some pretty volatile personalities just waiting to pop off against one another.
Ian Sterling, founder of Fishlab.com, began his aquarium journey over 30 years ago, driven by a deep fascination for fish and their diverse personalities. His website, Fishlab.com, is dedicated to making fishkeeping accessible and enjoyable, offering beginner-friendly guidance, expert insights, and a community for aquarists to connect and share experiences.