Can You Keep Oscar In 10 Gallon Tank?

If you’re a movie fanatic, you know Oscar awards. But, if you are a fish lover, you must definitely know about Oscar fish. It’s okay if you don’t know Oscar fish. That’s because Oscar fish is quite underrated in the fish-keeping hobby. And because there isn’t much information about keeping Oscar in tanks, people keep their Oscars in limited space. Like a 10 gallon or a 20-gallon tank. But, is it the right thing to keep Oscar in a 10-gallon tank?

No, a 10-gallon tank isn’t enough for a Cichlid that grows up to be 20 inches long. For a single Oscar Fish, a 55-gallon tank is an ideal size. Moreover, adding another Oscar will need an extra 30+ gallons in the tank which means two Oscars need an 85-100 gallon tank!

See, keeping this magnificent beast in a tiny 10-gallon tank just doesn’t cut it. Below, I will convince you why a 10-gallon tank isn’t enough, what’s the perfect size for your Oscar, and how to perfect your new tank for your Oscar. Let’s go.

Misconception About Oscar Fish Size

For a price of 10$, you can easily get one beautiful juvenile Oscar. The fish keepers sell their Oscars when they’re just tiny babies. That’s why you might think that Oscars are tiny fish that are easy to keep.

But, Oscars are a huge fish. An adult Oscar is on an average of 20 inches which is huge for aquarium fish! Moreover, only seasoned fish keepers can keep this beast in their tank.

There is also a common misconception that Oscars grow according to the tank size. But, this is false! If you keep Oscar in a small tank, the Oscar will be congested and will suffer greatly.

How Big Does An Oscar Grow?

Oscar fish can grow to be 20 inches long. From their 1 inch juvenile phase, by growing 1 inch every month, the adult Oscars grow pretty huge.

In captivity, Oscars grow up to 12 inches long. But, larger specimens are also recorded.

Moreover, the weight of an adult Oscar is almost 3 pounds. Now, that’s pretty huge!

Oscar And Water Volume Ratio

In the fish-keeping world, you can use the gallon rule for small fish like Neon Tetras, Cardinals, Platies, etc.

But, what formula can you use for an Oscar?

Well. Because Oscars grow huge, the gallon formula doesn’t work on them. Instead, we attribute that adult Oscars grow 12-18 inches in your tank. For each inch, we give 4 gallons of water. As a result, one Oscar needs around 55 gallons of water.

So, Can You Keep Oscar In 10 Gallon Tank?

Well. You can technically keep your Oscar fish in a 10-gallon tank. But, considering the size of them, a 10-gallon tank will be too small! So, you should NOT keep your Oscar in a 10-gallon tank.

Some reasons why you shouldn’t keep your Oscar in a 10-gallon tank are:

  • Oscar Fish needs lots of areas to swim around. Without sufficient space to swim, your Oscar gets stressed and may die. This is sad, considering that Oscars live for 20 long years in captivity!
  • Oscars are huge lovers of food. That’s why Oscar fish also secrete huge wastes. A 10-gallon tank doesn’t have enough good bacteria to remove the harmful ammonia. As a result, your Oscar will get ammonia poisoning and die prematurely.
  • Even for ethical reasons, a 10-gallon tank for a full-fledged adult is cruel. Oscars are intelligent and lovely fish. You wouldn’t want them to rot in a small tank with no area to swim around.

Exception: If you have a juvenile 2 inch Oscar, it’s fine to keep him in your 10-gallon tank.

What Size Tank Do You Need For Oscar?

If not 10 gallons, then how large should the tank size be for Oscars?

Well. The perfect size of tank for one Oscar fish is 55 gallons. And that is the minimum size. But, hey. If you’re looking for the ideal tank size, you should get a 75-gallon tank.

See, the larger the swimming space, the better it will be for your Oscar.

How Many Oscar Can You Keep In Your Tank?

If you are looking to keep 2 Oscars, then you might need an additional 30 gallons. So, for 2 Oscars you need a 75-gallon tank or better a 100-gallon tank!

Well, you can keep 4 Oscars in your tank too. But, you should buy a bigger tank of around 200 gallons. I think I can’t handle a large tank of 200 gallons. And, I definitely can’t handle so many large Oscars. That’s why many Oscar lovers like myself keep one or two Oscars in their tank.

I’d like to again remind you that if you decide to keep more than one Oscar in your tank, you need a larger tank.

Note: However, Oscars are perfectly fine with themselves. Oscar fish are introverts of the fish world, you see. Actually, you’ll notice that Oscars detest any fish around them, even if it’s their own kind. So, keeping just one beautiful Oscar in your 55+ gallon tank will be okay.

What Makes For A Perfect Oscar Tank?

The Oscars are difficult to keep. That’s why, if you are a beginner at fish keeping, you will not be able to handle an Oscar. These fish require lots of care and maintenance.

Well. If you already have an Oscar and you need some tips on how to set up an Oscar tank, here are some tips.


You might’ve already known by now that Oscars secrete huge wastes (thanks to their voracious appetite!). That’s why you should keep a powerful filter system for your Oscar tank. Otherwise, the huge wastes might cause an ammonia spike in the tank causing ammonia poisoning to your lovely Oscars.

If you decide to keep two Oscars, you need to buy an extra filter. Because, hey, I told you that Oscars are high maintenance!

Large Swimming Space

This entire topic is about tank size. And by now, you must’ve learned that Oscars grow pretty big. And, that you need to provide a large tank for even one Oscar fish.

This is how you care for your Oscar.

Compared to other aquarium fish, Oscar fish needs quite a huge tank (55 gallon+ for one Oscar). When you provide this environment to your Oscar, your Oscar will be playful and happy.


Oscars are lovers of warm water. Your Oscar will probably thank you when you maintain a temperature of 77° to 80°F.

To maintain temperature, you can buy a heater. And, to check the temperature you can attach a thermometer by the side of your tank.

Water Parameters

Perhaps, maintaining water parameters is the most important thing for your Oscar.

Oscar fish are really sensitive to water parameters. You might’ve heard about the head-in-the-hole disease which is fairly common in Oscar fish! This is caused by bad water parameters. That’s why, you should maintain a pH of 6-8, 12dH – 15dH water hardness, and frequently change your tank water.

Do Oscar Fish Need Tank Mates?

Like I mentioned earlier, Oscar fish are quite huge introverts. You should know that Oscar fish also get territorial when they think others are trying to take his space. So, I don’t recommend getting any tank mates for your Oscar. Also for the reminder, Oscars barely get lonely!

Also, Oscar may think of small fish as food because small fish easily fits in their mouth. That’s why small fish like Neon Tetras and Cardinals are a no. Shrimps also don’t belong in an Oscar tank.

If you think your Oscar can get lonely, you can get another Oscar. But, you need a larger tank, an extra filter, an extra EVERYTHING.

If you’re looking for other breeds, here are some you can keep as tank mates. These fish aren’t overly timid and small to be dominated by your Oscar. And neither are they aggressive to compete with an Oscar. So, these fish will be great. But, I still recommend you to not get any tank mates for your Oscar.

  • Catfish
  • Silver Dollar Fish
  • Fire mouth cichlids
  • Convict cichlids
  • Blue acara.


How Long Do Oscar Fish Live?

In wild, Oscars live for 15-20 years and they grow huge! In your tank, though, Oscars can live up to 12 years. If you’ve provided good care, then your oscar can live to be 15 years old.

Why Is My Oscar Turning Grey?

Oscar fish turn grey because they’re feeling stressed, scared, threatened, etc. This means your Oscar is feeling bad emotions.

If you see your Oscar turning from black to grey, you should remove any stimulus that’s causing this greying.


I hope this article was helpful in helping you select the perfect tank for your Oscar. For your adult Oscar fish, you need at least a 55-gallon tank. If you’re looking to keep more Oscars, you need a large tank of 100 gallons. Likewise, you need an extra filter for the more Oscar you add to your tank.

I also hope you don’t repeat the mistake of keeping your Oscar in a 10-gallon tank as my friend did. Happy fishkeeping.