Oscar Fish And Bettas: Can They Live Together?

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As a fish owner who loves mixing different kinds of fish, there was a point when I kept asking myself whether Oscars can live along with Bettas. I knew that both species are quite aggressive, although having them both in the same tank could be fascinating. That was when I began to research the topic a little deeper.

Yes, Oscar fish and bettas can share the same tank, although it is not recommended. Even though both species require similar water conditions, their size differences posses a significant issue. The Oscars could easily harm the Bettas and, in some cases, eat them as a whole.

However, if you wish to keep both creatures together, I will share with you a few techniques to reduce the aggression in your tank. More than that, I will show you which species can naturally get along with Oscars, with little effort from your side.

Also Read: 19 Great Oscar Fish Tank Mates

Can Oscars Live With Bettas?

Finding the appropriate tank mates for most fish could be difficult. But it is especially challenging where Oscars and Bettas are concerned because neither species is particularly easy to keep. It doesn’t take much for a tank full of Bettas to explode with violence. The same is right for Oscars. 

Admittedly, plenty of fish owners will tell you that they have successfully kept Oscars and Bettas in aquariums. As most professionals will say to you, fish are like humans. That is to say; they have distinct personalities. In other words, there are plenty of peaceful Oscars and Bettas in the world.

However, that doesn’t change the fact that Oscars and Bettas have a reputation for being problematic. If this has led you to conclude that Oscars and Bettas are not ideal tank mates, at least not for one another, you are absolutely right.

Do not pair Oscars with Bettas unless you have no other choice. There are far more ideal tank mates for Oscars than Bettas, and the reverse is also true. This pairing isn’t just an inconvenience. Any aquarist with aggressive fish will tell you that manifestations of violence in a tank can become a source of annoyance.

But in the case of Oscars and Bettas, unless you find a way to maintain the peace between these two species, you run the risk of losing your Bettas altogether. To better understand how an Oscar/Betta pairing would fair, consider the following:

1. Size Differences

While this isn’t the biggest issue, it is one of the most prominent. The difference in size between Oscars and Bettas is way too significant. Oscars are quite large Cichlids. The adult ones reach to roughly 12-18 inches.[1] Bettas, on the other hand, rarely exceed three inches.[2]

As a rule of thumb, most tank fish are willing to consume any creature they encounter that can fit in their mouth. Oscars are no different. In fact, they are far worse than the average aquarium fish because they also feature an aggressive streak.

As such, they are less likely to ignore the smaller creatures they come across in the tank. An Oscar is more than willing to eat any fish that is half its size or smaller. And unfortunately, Bettas fits perfectly within that bracket. The fact that they are not the most peaceful of fish only makes the situation worse.

  • Even though the following Youtube is pretty low-quality, it plainly says it all. As you can see, Oscars are more than capable of eating Bettas, sometimes as a whole. 

2. Temperament Issues

This is the source of all your problems. Yes, Oscars and Bettas differ in size. But fish of dramatically different sizes can live together if they have the right temperaments. Unfortunately, Oscars and Bettas do not have the proper nature.

In the 19th Century, Betta fighting was a sport. Betta fish were such vicious creatures that they would engage in such violent confrontations to the point their clashes became a source of entertainment.[3]

The Bettas found in most aquariums today are no less aggressive. They are capable of harming and even killing one another. Male bettas are especially aggressive. Unfortunately, they are also the most attractive, which is why people are not necessarily compelled to raise female bettas (even though they are far less violent).

Bettas have one encouraging attribute. Yes, they are aggressive. But that aggression is typically targeted towards other bettas. This is why they can exist without incident in many aquariums. If you can pair them with other peaceful species, they will only fight amongst themselves, allowing a modicum of tranquility to settle over the tank.[4]

This is why they cannot coexist with Oscars. Oscars are aggressive, and the fighting between Bettas in your tank is going to draw their attention.[5] A confrontation between Oscars and Bettas will likely end with the Oscars either eating the Bettas or nipping their fins off. 

You should keep in mind that Oscars are predatory. For many of them, any betta you add to the tank is just a snack waiting to be consumed. Even though Bettas are aggressive themselves, they stand no chance against Oscars.

3. Similar Food Requirements

Like most other freshwater fish, Bettas and Oscars share close feeding requirements. Ideally, you should feed both creatures with high-protein meals. That may include pellets, flakes, freeze-dried, live, and frozen foods.

Since they both swim in the middle and top sections of the tank, they are likely to compete over food. The minute you pour the nutrients down, you will notice the arising competition. Here, the Oscars also have the upper hand. 

When malnourished, your Bettas will probably get sluggish, developing diseases along the way. In some cases, your Oscars could even chase down your Bettas as they see them as a feeding source threat. That could end up with ripped fins and possibly dead fish. 

4. Water Requirements

This is the only category that supports the coexistence of Oscars and Bettas. Like many cichlids, Oscars live in waters whose temperature ranges from 75 to 80 degrees F.[6] Also, they require a pH of 6 to 8. While they can tolerate a wide range of water hardness, you should keep it between 12 and 15 dH.

However, if you are new to fishkeeping, those figures could mean nothing to you. What you need to understand is this: Bettas have similar requirements where the parameters of their water are concerned. They thrive in temperatures ranging from 76 to 82 degrees F and a pH ranging from 6.5 to 7.[7]

Simply put, Bettas and Oscars can live and thrive within the same water conditions. Therefore, even though they are not the best tank mates, you can force them to coexist in the same tank.

Also Read: Can Angelfish And Oscars Live Together?

How to Make Oscars and Bettas Coexist?

Keeping Oscars and Bettas in the same tank is neither easy nor encouraged. But it can be done if you take the following precautions:

1. Get a Large Tank

Your Oscars and Bettas should be housed in the most massive tank you can afford. Bettas can survive in a container that is as small as 10 gallons. However, Oscars need at least 55 gallons. You should also keep in mind that Oscars and Bettas are pretty territorial. 

Nevertheless, if you can give them ample space, they can claim their own territories without crossing into one another’s domains. That is why I also recommend getting a relatively long tank. When both species have enough room to swim horizontally, things are likely to remain calm.

2. Introduce Plants and Decorations

Give your bettas plenty of hiding places by adding plants and decorations to their tank. You should also pick those plants that are large enough to contend with the Oscars’ fins. They have been known to rearrange aquariums during their swim. 

Also, the Bettas in your tank will appreciate the opportunity you have given them to escape the bullying attention of the Oscars. As long as they remain out of sight, your Oscars are less likely to show interest in your Betta fish. 

3. Consider the Number of Fish

Oscars are most dangerous when they are alone. Therefore, you should either keep them in pairs or groups of more than five. This will dilute their aggression. However, you should also keep in mind that Oscars are quite messy. 

The larger the group of Oscars you have, the more difficult maintenance will become. That brings us back to the aquarium’s dimensions. A 55-gallons tank should be sufficient to occupy a group of Oscars while remaining the environment relatively diluted.   

Bettas, on the other hand, should be kept without any partners of the same kind. They aren’t a schooling fish, and they tend to get pretty aggressive if forced to swim along with other Bettas. Hence, a group of Oscars with a single Betta fish is the ideal scenario.[8] 

4. Choose the Right Genders

If conflicts among your Bettas are causing disruptions in the tank, eliminate some of the males. As mentioned earlier, Bettas are not necessarily schooling fish. They can live singly in a tank. But if you have chosen to house multiple Bettas, reduce the number of males.[9] 

Add some females to the equation. You can also choose to house only females; though, the males are more physically attractive. However, none of these techniques can guarantee positive results. 

The chances that your Oscars will eat your Bettas are still quite high. But that shouldn’t stop you from experimenting. If you persevere, you could stumble upon a set of conditions that allows Oscars and Bettas to coexist peacefully.

Also Read: Oscar Fish And Goldfish: Can They Live Together?

What Kind of Fish Can You Put with Oscars?

Oscars prefer living in groups even though they are large and aggressive. The key to finding the right tank mates for them is to avoid any fish that are smaller than five inches. You are also discouraged from adding fish that are too shy or timid. 

These will face the risk of going hungry if they fail to compete for food with the Oscars. If at all possible, you should prioritize bottom-dwellers, fish that will steer clear of the Oscar. With that in mind, some suitable companions for your Oscars include:[10]

  • Silver Dollars – Silver dollars are highly popular fish that can grow to a size of 6 inches. More importantly, the shape of their bodies makes them look larger. This will discourage your Oscars from eating them. If possible, get a group of Silvers. A single one will be an easy target.
  • Severum Cichlid – At 8 inches, not only are Severum fish large, but they are also quite docile. They spend a lot of time minding their own business. As such, they are less likely to alienate your Oscars. And even if a conflict erupts, they are strong enough to survive confrontations.
  • Jack Dempsey – At 10 inches, this is a pretty large fish. However, the species is known for being both docile and aggressive. You can never know what you will get until you have added the fish to your tank. But even if you land an aggressive fish, it is unlikely to intimidate your Oscar. The two creatures will balance one another out.
  • Plecostomus – Plecos are primarily known for the sharp spines on their fins. These spines are more than capable of killing an Oscar that wants to eat a Pleco. This makes Plecos a threat to Oscars. Hence, they are not ideal tank mates for aggressive Oscars, and you should only introduce them if you have a large tank that will permit both creatures to steer clear of one another. 
  • Green Terror – At 8 inches, your Oscar has no real hope of bullying a green terror. These creatures can hold their own against Oscars. In fact, they could become a threat to your Oscars unless you introduce them to the tank when they are still smaller than the Oscar.


If you wish to keep Bettas and Oscars in the same aquarium, the bottom line is that you shouldn’t. Since both species are aggressive, they are very likely to hassle one another. Then, their size differences will play the role, and your Oscars will gain the upper hand. 

However, that isn’t the end of it. You could always pair your Oscars with different kinds of fish. Stick with those that are relatively large, like Silver dollars or Green terrors. Either way, you choose, I wish you the best of luck in raising these beautiful, fascinating creatures. 


  1. https://www.ratemyfishtank.com/blog/the-ideal-tank-setup-for-oscars
  2. https://www.ratemyfishtank.com/blog/can-you-keep-other-fish-with-your-betta
  3. https://petcentral.chewy.com/best-betta-fish-tank-mates/
  4. https://pets.thenest.com/happens-cichlid-betta-placed-same-fish-tank-4043.html
  5. https://coolfish.network/oscars-fighting-how-can-you-stop-it/
  6. https://fishkeepingadvice.com/oscar-fish-care-guide/
  7. https://www.petsit.com/facts-about-betta-fish
  8. https://animals.mom.me/can-stop-bettas-fighting-10002.html
  9. https://japanesefightingfish.org/betta-fish-fight/
  10. https://www.buildyouraquarium.com/oscar-tank-mates/