Are Oscar Fish Aggressive? (Best Tank Mates for Oscar Fish)

Are Oscar Fish aggressive? This is the question many Aquarists have when they want to keep Oscar Fish in their tank.

In this article, I am going to answer this question.

Oscar Fish are aggressive. But you can keep other passive fish that are similar to the size of your Oscar Fish in your Oscar Fishtank.

Are Oscar Fish Aggressive? (Best Tank Mates for Oscar Fish) image

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Compatible Oscar Fish tank mates

Oscar Fish belongs to the Cichlids family and they are known for their aggressive behavior.

That’s why it is very difficult to find compatible tankmates for Oscar Fish.

While choosing tankmates for Oscar Fish you have to keep a couple of things in mind:

  1. The fish should be similar to the size of Oscar Fish or it should be a large fish. So that the Oscar Fish will not be able to eat it.

If you keep small fish like Neon tetra, Guppies with your Oscar Fish then they are most likely going to get eaten.

  1. You should choose the fish that are passive or a little bit aggressive so that they can hold on their own in the Oscar Fish tank.

If you keep these things in mind then you can easily choose tankmates for your Oscar Fish.

Below are a few examples of good tank mates for Oscar Fish.

Best Tank Mates for Oscar fish

1. Bichirs

Bichir

Image by Stan Shebs under CC BY-SA 2.5

PARAMETERSVALUES
FISHBichirs
SCIENTIFIC NAMEBichir
FAMILYPolypteridae
CARE LEVELIntermediate
MAXIMUM SIZE30 inches
AVERAGE LIFESPAN15-20 Years
DIETCarnivore
WATER TEMPERATURE77-84° F
WATER pH5-7.5
WATER HARDNESS8 - 12 dGH
BREEDINGEgg layers
MINIMUM TANK CAPACITY90 Gallons

Bichirs are one of the best tank mates for your Oscar Fish.

Bichirs are bottom dwellers so they spend most of their time near the bottom of the tank.

So they will not bother your Oscar Fish because Oscar Fish usually spend most of their time in the middle of the tank.

They can even walk on the substrate of your tank.

And I am not kidding!

In fact, scientists are trying to grow Bichirs on the land just because of their ability to walk.

Besides, Bichirs are also nocturnal fish which basically means that they usually stay active during the night and feed during the night. 

So they will not bother your Oscar Fish during the day.

They are also moderately aggressive fish so they can hold their own against Oscar Fish.

Also, they can grow as large as 30 inches so there is no way that that they can fit into the mouth of your Oscar Fish.

But, as they grow very big, you will also need to keep them in a large tank of at least 90 gallons.

Talking about food Bichirs fish are carnivorous fish.

In the wild, they feed on crustaceans, insects, small vertebrates and fishes.

In your aquarium, you can feed them pellets, frozen or dried bloodworms, brine shrimp, feeder fish, etc.

You can also feed them meat such as oxheart and earthworm etc.

While feeding them flakes and pellets make sure that you are using high-quality sinking flakes and pellets.

The ideal water parameters for Bichirs are as follows:

  • Temperature between 74 to 81° Fahrenheit
  • pH between 6 to 8
  • Hardness between 5 to 20 KH

As you can see the ideal water parameters that Bichir fish require is similar to Oscar Fish so you can easily keep them together in the same tank.

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2. Convict cichlid

Convict cichlid

Image by Deanpemberton under CC BY-SA 3.0

PARAMETERSVALUES
FISHConvict Cichlid
Common namesZebrafish
SCIENTIFIC NAMEAmatitlania nigrofasciata
FAMILYCichlidae
CARE LEVELModerate
MAXIMUM SIZE6 inches
AVERAGE LIFESPAN8+ Years
DIETOmnivore
WATER TEMPERATURE79 and 84°F
WATER pH6.6-7.8
WATER HARDNESS6 – 8 dGH
BREEDINGEgg layers
MINIMUM TANK CAPACITY30 Gallons

Convict cichlid is another good tankmate for Oscar Fish.

They are also known as Zebra cichlids because of the black stripes on their body.

Convict cichlids belong to the cichlids family that are known for their aggressive behavior.

So they can hold their own against Oscar Fish.

Convict cichlids are also very easy to care for so they are an ideal choice for beginners.

They are very active fish and can easily survive in Oscar Fish tank.

Convict cichlid spends most of their time within their territory i.e. inside caves or plants so they will not bother you Oscar Fish.

Besides, convict cichlids can grow up to 6 inches so they are not small enough to fit into the mouth of your Oscar Fish.

The males are larger than the females.

The males can grow up to 6 inches and the females grow a maximum of 4.5 inches.

Talking about diet, Convict cichlids are not very fussy eaters and can eat anything you put inside their tank.

They are omnivorous and you can feed them flakes and pellets.

You can also feed them meaty food such as bloodworms, daphnia, brine shrimp, blackworms, etc.

As they are omnivorous you should also feed them blanched vegetables such as carrots, broccoli, lettuce, etc.

The ideal water parameters for convict cichlids are as follows

  • Temperature between 79 to 84° Fahrenheit
  • pH between 6.6 to 7.8.
  • Hardness between 6 to 8 GH

As you can see, these water parameters are similar to ideal water parameters that your Oscar Fish require.

So you can easily keep them together in the same tank.

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3. Firemouth Cichlid

Firemouth Cichlid
PARAMETERSVALUES
FISHFiremouth Cichlid
SCIENTIFIC NAMEThorichthys meeki
FAMILYCichlidae
CARE LEVELEasy
MAXIMUM SIZE7 inches
AVERAGE LIFESPAN15 years
DIETOmnivorous
WATER TEMPERATURE75-86°F
WATER pH6.5-8.0
WATER HARDNESS8-15 dGH
BREEDINGLive bearers
MINIMUM TANK CAPACITY30 gallons

Firemouth cichlids are bright colored fish that can add vibrant colors into your aquarium.

This fish is very hardy and easy to care for which makes it an ideal choice for beginners.

They are usually very peaceful fish but can get very territorial especially during the spawning season.

And they can hold their own against Oscar Fish.

Firemouth Cichlid can grow up to 6 inches so they will not fit into the mouth of your Oscar Fish.

Besides, they are not fussy eaters and will readily eat anything you put into the tank.

They are omnivorous and you can feed them meaty food such as frozen or dried bloodworms, brine shrimp, daphnia, etc.

You can also feed them flakes and pellets.

As they are omnivorous you should also feed them vegetables such as carrots, zucchini, lettuce, etc.

The ideal water parameters for Firemouth Cichlid are as follows:

  • Temperature between 75 to 86° Fahrenheit
  • pH between 6.5 to 8 
  • Hardness between 8 to 15 GH

So the ideal water parameter range of Firemouth Cichlid is similar to that of Oscar Fish so you can easily keep them together in the same tank.

4. Silver Dollar

Silver Dollar

Image by Haplochromis under CC BY 2.0

PARAMETERSVALUES
FISHSilver Dollar
FAMILYCharacidae
CARE LEVELIntermediate
MAXIMUM SIZE6 inches
AVERAGE LIFESPAN10 years
DIETOmnivores
WATER TEMPERATURE75-82°F
WATER pH5.5-7.5
WATER HARDNESS4-18 dGH
BREEDINGEgg layers
MINIMUM TANK CAPACITY75 gallons

Silver Dollar is one of the best schooling fish you can keep with your Oscar Fish.

Silver dollar fish get their name from their appearance.

They are silver in color and they have flattened laterally flattened body so they look exactly like an old silver dollar.

Silver dollar are peaceful schooling fish.

You may be wondering, as Silver dollar is a peaceful fish it may not be a good fit for Oscar Fish tank.

But the thing is, Silver dollar is a schooling fish and you should keep them in at least a group of 5 in your Oscar Fish tank so that the Oscar Fish will not be able to target only one fish.

Besides, Silver dollars grow up to 6 inches so they are big enough to not fit into the mouth of your Oscar Fish.

Talking about their food, they are omnivorous fish.

But their diet primarily consists of plant matter.

You can feed them a variety of vegetables such as Cucumber, Lettuce, and Spring greens.

As they are omnivorous, you should also treat them regularly with Bloodworms, Brine shrimp, etc.

You should feed them a couple of times per day.

And you should feed the amount of food they can consume within 3 minutes or less each time.

Talking about the ideal water parameters for Silver dollar fish

  • The ideal temperature range is between 75 to 82° Fahrenheit.
  • Their pH tolerance range between 5.5 to 7.5
  • And hardness tolerance range is between 4 to 18 GH.

Their ideal water parameter range is quite similar to that of Oscar Fish. So you can easily keep them both together in the same tank.

5. Sailfin Pleco

Sailfin Pleco

Image by Wisky under CC BY-SA 3.0

PARAMETERSVALUES
FISHSailfin Pleco
COMMON NAMESSailfin pleco, leopard pleco, gibby pleco
SCIENTIFIC NAMEPterygoplichthys gibbiceps
FAMILYLoricariidae
CARE LEVELEasy
MAXIMUM SIZE19 inches
AVERAGE LIFESPAN20 years
DIETOmnivorous
WATER TEMPERATURE77-79 °F
WATER pH6.5-7.4
WATER HARDNESSKH 6-10
BREEDINGEgg layers
MINIMUM TANK CAPACITY100 gallons

Sailfin Pleco is a freshwater catfish.

As the name suggests, Sailfin Plecos have a fin that looks like a sail of a boat.

These are quite large fish that can grow up to 19 inches so there is no way they can fit into the mouth of your Oscar Fish.

But as they can get very large, you will also need a large tank of at least 100 gallons to keep them.

Besides, Sailfin pleco is a nocturnal fish so it will stay active during the night.

And during the day it will mostly hide near ornaments or driftwood or plants in your tank.

So they will not bother you Oscar Fish during the day.

They are also bottom feeders so they spend most of their time near the bottom of the tank.

Sailfin Plecos are omnivorous but their diet mostly consists of plant matter.

And they mostly feed on algae.

So they will help to keep algae in control in your tank.

If your tank does not have algae only then you will need to feed this fish.

Its diet mostly consists of algae-based food like algae wafer.

And you can also feed it fish pellets and dead meat like frozen or dried bloodworms, brine shrimp, etc.

Talking about water conditions of Sailfin Pleco,

The ideal temperature range is between 77 to 79° Fahrenheit.

Its pH tolerance range is between 6.5 to 7.4 

And hardness tolerance range is between 6 to 10 KH.

So the ideal water parameters range of Sailfin Pleco is similar to Oscar Fish.

So you can easily keep them in the same tank.

oscar fish tank mates

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Do Oscar Fish fight each other?

Yes, Oscar Fish fight each other. There are several different ways they fight with each other but the most common way is Jaw or Lip locking.

This is when they try to grab each other’s mouths.

How to stop Oscar Fish aggression?

There are several ways you can try to reduce and stop Oscar Fish aggression.

But there is no surefire way to stop aggression among your Oscar Fish because every fish has a different personality.

So you will have to try the following ways one by one and see what works for you.

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Ways to Stop Oscar Fish Aggression

ways to stop oscar fish aggression

1. Provide a larger tank

Oscar Fish can get very big and it requires a lot of space to swim around.

If you keep them in a very small tank then it is very common to see aggression among them.

The ideal tank size for Oscar Fish is 55 gallons for a single Oscar Fish and then extra 30 gallons for every new addition.

So if you are keeping your Oscar Fish in a smaller tank then upgrading the tank can help to stop aggression.

2. Add another fish

Now adding another fish in the tank where the Oscar Fish are already very aggressive may not sound like a good idea.

But if you add a few active fish in the Oscar Fish tank then it will help to spread their attention and may result in reduced aggression among them.

A few good examples of hardy fish you can add into your Oscar Fish tank are Black convict cichlids, Bluegill, etc.

3. Rearrange your tank

Oscar Fish are territorial and they form their territories in your tank.

And if other fish invade in their territory they get aggressive.

So if you rearrange your tank then the Oscar Fish will have to create their territory again and this can help to reduce aggression.

You can rearrange your tank once a week while you do the water change.

You don’t have to completely rearrange your tank. You can just place your ornaments in a random position every time you rearrange the tank.

4. Make some hiding places

Though Oscar Fish is a very large and aggressive fish, they also sometimes need to cool down and rest alone.

So if you provide it some good hiding places where it can stay alone and cool down, it may help to reduce aggression.

You can create hiding places in your tank by adding some plants and creating some caves in your tank.

5. Keep your fish well-fed

If you are not providing sufficient food to your Oscar Fish then this could be the reason for aggression.

So you should feed sufficient food to your Oscar Fish.

If the Oscar Fish is less than 5 inches then you should feed it three times per day.

And you should feed it the amount of food it can consume within 3 minutes.

When the Oscar Fish in small i.e. less than 5 inches, you should feed it more live food.

If you have Oscar Fish that is larger than 5 inches then you should feed it twice a day.

And you should feed it the amount of food it can consume within 3 minutes.

For Oscar Fish that are larger than 10 inches, you should feed it once a day.

6. Provide a healthy environment

Oscar Fish can get irritated if it’s not getting a healthy environment.

So you should regularly check water parameters such as ammonia levels, the temperature, pH of the water, and hardness of the water regularly.

And make sure that it is in control and within the ideal range that and Oscar Fish prefers.

The ideal temperature for Oscar Fish is between 74 to 81° Fahrenheit.

Its ideal pH tolerance range is between 6-8 and the hardness tolerance range is between 5 to 20 KH.

Ideally, your tank should not contain any ammonia.

If you notice high ammonia levels then you can use these ways to reduce the ammonia and get rid of it.

Oscar Fish prefers warmer water so if the water temperature of your tank is below the ideal range then you should introduce a heater into your tank to raise the temperature. Checkout our heater recommendation

If the temperature is well above the ideal range then these are the ways to reduce the temperature in your tank.

You should also make sure that your tank contains optimum levels of oxygen.

If you notice any signs of low oxygen like the fish is coming to the surface gasping for air, rapid gills movement then you should use these ways to increase oxygen in your tank.

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Conclusion

Oscar Fish belongs to the Cichlids family and they are known for aggression.

Oscar Fish are no exception and they can be very aggressive and territorial.

Usually, providing ideal environment in the tank is the solution to reduce aggression among Oscar Fish.

This includes providing a larger tank and maintaining ideal water parameters like temperature, pH, hardness, and the ammonia levels should be in control.

I hope you found this article helpful.

If you do, please share it!

As always, happy shifting fish keeping!

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