Oscar Fish Behavior And Intelligence (Everything You Need To Know)

Oscar fish are one of the most loved fish in the aquarium hobby for a good reason.

They are known to be very smart fish and their behavior is quite interesting.

In this article, I’m going to cover everything you need to know about Oscar fish behavior and intelligence.

Oscar fish is known to be a very aggressive fish so you should avoid keeping any small fish in the Oscar fish tank.

Besides, Oscar fish is also one of the most intelligent fish in the aquarium hobby.

Oscar Fish Behavior in a New Tank

Oscar fish are known for their aggressive behavior.

But if you introduce juvenile Oscar fish in your tank then you will not see any aggression.

Actually, Oscar fish not very aggressive fish.

But they will eat whatever fish that fits into their mouth that’s why people consider Oscar fish a very aggressive fish.

If you introduce a large Oscar fish in your tank then usually you will not see any signs of aggression right away.

Also, you may never see any aggression if you keep the large the fish in a large tank (according to its size) and the tank contains compatible tank mates.

If you introduce the large Oscar fish in a relatively smaller tank then after some time you may see aggression.

Because Oscars are territorial fish and they create their own territory in the tank.

And if any other fish enter their territory then they get aggressive and chase them out.

So if you are going to introduce a large Oscar fish in your tank make sure that your tank is large enough for it.

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Oscar Fish Aggressive Behavior

Oscar fish are known for their aggressive behavior.

There are several different ways Oscar fish fight with each other.

• The most common way is Jaw-locking or Lip-locking. This is when they are head-to-head on each other.

• Oscars also fight with each other by chasing or pursuing each other.

Why Oscar fish fight?

There are a few reasons Oscar fish fight with each other.

• The most common reason Oscar fish fight with each other or any other species of fish is if they are not getting sufficient space. Oscar Fish are territorial and they form territory in the tank. And when other fish enter their territory they attack other Oscar or species of fish.

• Oscar fish fight with each other or with any other species of fish if they are not comfortable with it.

• Oscar fish fight with each other to show their dominance

• If Oscar fish are competing with other fish for food then this can result in aggression.

• If the Oscar fish is not getting the ideal environment for example, if the4 water parameters of the tank don’t match the ideal water parameters range of Oscar fish then you may see Oscar fish aggression.

How to stop Oscar fish aggression?

There are several things you can do to stop Oscar fish aggression.

Larger tank

Oscar fish can get very large. It can grow up to 12 inches and even 15 inches if you take good care of it.

Also, it can grow very fast. It can grow at a rate of 1 inch every month.

As Oscar fish grows pretty large it also requires a larger tank.

A single Oscar fish requires at least a 55-gallon tank.

So if you are keeping Oscar fish in a small tank then upgrading the tank to a larger tank can help to stop aggression.

Ideal environment

If Oscar fish is not getting the ideal environment then this can also result in aggression. So you should make sure that your tank has the ideal environment for Oscar fish.

You should also make sure that your tank water is clean and clear.

And it does not contain any ammonia.

If you noticed high ammonia levels in your tank then you can use these ways to reduce the ammonia and get rid of it.

Oxygen

Your tank should also contain optimum levels of oxygen.

There are a few signs that suggest that your tank does not contain sufficient oxygen.

If you notice your fish are coming to the surface of the tank is gasping for air then this is a sign that your tank has low oxygen levels.

If you notice that your fish is not moving around as often and quickly as is used to be then this could be the sign that your fish tank contains low oxygen.

So if you notice any of the above signs then you can use these ways to increase oxygen in your tank.

Oscar fish prefers warmer water so you should provide it warm water anywhere between 74 to 81° Fahrenheit.

Other ideal water parameters for Oscar fish are as follows:

• pH between 6-8 
• Hardness between 5 to 20 KH.

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Try rearranging your tank

Rearranging the tank can also help to reduce Oscar fish aggression.

So if your Oscar fish keeps fighting with each other then while doing the weekly water change you should rearrange your tank a little bit.

It could be as simple as moving the rocks in your tank to a different place.

Oscar fish like to design their tank so when you rearrange the tank Oscar fish will have to rearrange it again which will keep it busy and distract it from fighting.

Food

If your Oscar fish compete with each other or other species of fish for food then this can also encourage aggression.

So you should make sure that you are feeding them sufficient food.

Compatible tank

If you are keeping small fish or very aggressive fish with your Oscar fish then this could be the reason for aggression.

So, in this case, you should move the small or aggressive fish to another tank or keep Oscar fish in a separate tank.

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Oscar Fish Breeding Behavior

Image by Retro Lenses under CC BY 4.0

Breeding Oscar fish can be a very difficult task.

Oscar fish are very picky when it comes to choosing a mate.

Also, it is very difficult to identify male and female.

You’ll be able to distinguish male and female only when female lay eggs.

To breed Oscar fish, you can either get a pair of already spawned Oscar fish or you can get a group of 8 juvenile Oscar fish, keep them in the same tank and then identify the pair and keep it separate in a breeding tank.

There are a few behavioral signs that suggest that your Oscar fish are ready to breed.

• When Oscar fish are ready to breed they usually flare their gills and fins to notify other mates.

• Oscar fish lay their eggs on large flat surfaces so when they are ready to breed they will start cleaning the surface that could be the surface of the stone in your tank with their mouth.

From these behaviors, you can easily know your Oscars are ready to breed.

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Baby Oscar Fish Behavior

Image by Daniella Vereeken under CC BY 2.0

When you keep baby Oscar fish in the same tank they look very cute as a puppy.

When Oscar fish are small they don’t show any signs of aggression.

And you can keep other small species of fish with them.

But remember Oscar fish are very fast growing fish. They can grow at a rate of 1 inch per month.

So eventually you will have to put them in a large tank.

Also don’t think that just because Oscar fish had been living with other small species of fish from a very young age it will not eat them.

When your Oscar fish get bigger it will not bother to eat any other fish that can fit into its mouth.

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Oscar Fish Intelligence

Oscar fish is known to be one of the most intelligent fish in the aquarium hobby.

You can clearly see its intelligence by just watching it for a few minutes.

This fish doesn’t just move around mindlessly.

Every time it swims in the tank it seems like it has some purpose for moving in the tank.

Oscar fish is also known to be very affectionate fish.

And they can recognize their owners.

This is the reason they are also known as water dog or river dog.

When Oscar fish are small they look similar to puppies.

You can also feed your Oscar fish with your hands.

But you have to follow a few precautions while feeding your Oscars with your hands.

• First of all, you should make sure that your hands do not contain any kind of chemicals or soap residuals.

• When you want to feed your Oscar fish with your hand, don’t directly put your hand into the tank. Instead, fold your hands and make a fist then slowly unfold your hand. This way Oscar fish will not think your fingers as worms and try to eat.
• You may not get it right in the first attempt it may take some time and practice. But eventually, your Oscar fish will recognize your hand and will not confuse it with worms.
• You should also avoid touching your Oscars very often because it can damage their protective membrane.

They redesign the tank

If you have kept Oscar fish for a while then you may have noticed a change in the look of your tank.

This is because Oscar fish can redesign the tank according to their taste.

You will often find Oscar fish moving the rocks and gravel in the tank.

They can also uproot plants in your tank if they don’t like it. That’s why if you want to keep some live plants in an Oscar fish tank, you should choose plants that create complex root structures in the substrate.

Oscars are moody

You will also find Oscar fish sulking in the tank quite frequently.

The thing is Oscar fish are quite moody fish and when they don’t like anything in their tank then they stay in one place without moving.

This behavior can also make you think that your Oscar is dead.

Oscar fish usually sulks when they notice any change in their tank and they don’t like it.

That could be the change in their food, water temperature, etc.

But they will not just keep sulking for a long time.

They will start moving again after a couple of hours.

If you notice your Oscar fish is staying at one place without moving for a very long time then this could be because it is ill or the water conditions of your tank are not ideal for your Oscar fish.

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Oscar Fish Tank Mates

Due to their aggressive behavior, it is quite difficult to find the right tank mates for your Oscar fish.

But if you keep a few things in mind, you can easily choose other species of fish to keep with your Oscar fish.

While choosing tank mates for your Oscar fish make sure that it is not very small in size. 

• If the fish is very small in size i.e. if it can fit into the mouth of your Oscar fish it is most likely going to get eaten by the Oscar.

• The second thing is you should keep other fish that are moderately aggressive and can hold their own against Oscar fish.

Usually, other Cichlids are very good tank mates for your Oscar fish.

Because they are relatively large and as they belong to the cichlid family, which is known for aggressive behavior, they can hold their own against Oscar fish.

Some good examples of Cichlids you can keep with your Oscar fish are as follows:

• Convict cichlids
• Firemouth cichlid
• Green terror cichlid
• Jaguar cichlids
• Severum cichlids
• Jack Dempsey

Besides, you can also keep other fish that are large enough to not fit into the mouth of your Oscar fish and can hold their own against them.

Some good examples of such fish are as follows:

• Bichir
• Silver Arowana
• Pleco
• Silver Dollar

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Keeping Oscar Fish Together

As Oscar fish are aggressive, ideally, you should keep Oscar fish in a species only tank.

You can keep as many Oscar fish together as you want, just make sure that you are providing them enough space to swim around.

Also, there should not be a very large difference between the size of the Oscars.

Because bigger Oscar can bully small Oscar fish.

A good rule of thumb to follow while deciding the tank size for Oscar fish is 55 gallon for your first Oscar fish and then another 20 gallons for every new Oscar fish.

FAQ

Why does Oscar fish move rocks?

Oscar fish are very intelligent fish and they can redesign their tank according to their taste.

Moving the rocks in the tank is one of the things they do to redesign their tank.

Besides, they also move the gravel in the tank and can uproot the plants if they don’t like it.

How do I make my Oscar fish happy?

To keep your Oscar fish happy, you should provide the ideal environment to the fish and feed it a balanced diet.

You should maintain the ideal water parameters in your tank.

The ideal water parameters for Oscars are as follows:

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

Besides, you should also make sure that your tank does not contain any ammonia.

And make sure that your tank contains optimum levels of oxygen.

Oscar fish is omnivorous but their diet mostly consists of meaty foods.

So primarily, you should feed them Cichlid flakes and pellets.

Occasionally, you should also feed them live or frozen food like live bloodworms, brine shrimp, etc.

As Oscars are omnivorous, you should also feed them vegetables such as boiled peas, spinach, lettuce, cucumber, carrot, etc.

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Do Oscars play dead?

Oscar fish are very moody and if there is something that they don’t like in their tank, they will stay in one place without moving.

This might confuse you that your Oscar fish is dead.

But this is a very common behavior of Oscar fish when they don’t like any change you made in their tank that could be the change in their diet, the temperature of the water, etc.

How do you entertain an Oscar fish?

There are various ways you can entertain your Oscar fish.

Get him a tank mate

If your Oscar fish is the only fish in the tank then the simplest way to keep it engaged and entertained is by getting him a tank mate.

Ideally, you should get him other Oscar fish of similar size.

Get him a toy

You can also introduce a toy like a ping pong ball in your tank and your Oscar fish will play with it.

You just have to keep the ping pong ball floating on the surface and the Oscar Fish will hit it.

Caves and tubes

Oscar fish loves to go into caves and tubes.

So you can introduce some caves and tubes in your tank to keep it entertained.

If you have multiple Oscar Fish then these caves will also provide hiding places to the fish.

Besides, it will also give an aesthetic look to your tank.

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Conclusion

So this was everything you need to know about Oscar fish’s behavior and its intelligence.

I hope you found this article helpful.

If you do, please share it.

As always happy fish keeping!