What Tank Setup Do You Need for an Oscar Fish

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Oscar fish are one of the most popular cichlids among both new and veteran fishkeepers alike. While there are over 2,000 varieties of cichlids found throughout tropical climates like South America and the Amazon River, Oscars are often the top pick. They’re frequently cross-bred to create new and unique varieties, too.

Also called the marble cichlid, velvet cichlid or tiger Oscar, these fish can live anywhere between 10 and 20 years! The key is choosing the right Oscar fish tank size and understanding a few nuances of Oscar fish care.

Keep reading for all the important details you’ll need to give your new fishy friend a long, happy life. You’ll also find a complete Oscar fish tank setup shopping list near the end of this guide. Let’s dive in!

How Big Do Oscar Fish Get?

Oscar fish swimming in a tank

In the wild, the average Oscar fish size is around 18 inches, but in captivity, they rarely get bigger than 10 to 12 inches. It’s not completely unheard of for a pet Oscar to exceed this range, though, so be prepared for the possibility.

As for weight, a 12-inch long Oscar will weigh around 2 and 1/3 pounds. And these big fish need a fair amount of food to stay healthy! You’ll need to feed yours around between once per day or once every other day.

Do Oscar Fish Need Tank Mates?

When it comes to whether Oscars need tank mates, they actually do quite well living alone. Because they can get so large, it’s sometimes difficult to find fish that pair well with them. You’d definitely need bigger fish that won’t fit in the Oscar’s mouth, otherwise they’re likely to get eaten.

Oscars can also be territorial and assertive, so any tank mates need to be able to hold their own during feeding times. Lastly, keep in mind that your Oscar fish will prefer the top to mid-level of your tank.

Tank mates that prefer the bottom of the tank and who aren’t shy will be your best bets. Catfish, Convict cichlids, and Silver Dollar fish are usually safe choices.

What Size of Tank Do You Need for Oscar Cichlids?

oscar fish tank

Because Oscars can get so large, you need a minimum 55-gallon aquarium. Ideally, you should get a 75-gallon or larger tank, especially if you plan on putting any other fish in the tank.

The larger tank is best because large fish—like Oscar fish—make large amounts of waste. And the bigger your tank is, the slower your tank water will become dirty.

You should plan on getting a cover or lid for your tank. Oscars can and do jump!

What Filter Should I Get for Oscar Fish?


Oscars eat quite a bit of food, so you will need a good filtration system to keep the water suitable. Go for a sturdy, high-performance, high-quality filtration system. A powerful canister filter connected to a spray bar will keep the water clean and evenly circulated. It’s also recommended that your filtration should be able to turn over the volume of water in the tank every 15 minutes.

It’s also recommended that your filtration can turn over the volume of water in the tank every 15 minutes. So, let’s say you have a 55-gallon aquarium. It’s always wiser to choose a filter that can handle up to 70 gallons versus one that maxes out at 55 gallons.

oscar cichlid

Do Oscar Fish Need An Air Pump?

tank air pump

Oscar fish don't need an air pump, provided the tank is getting enough oxygen. So long as you opt for a good filter that keeps the tank water moving, your Oscar fish should be okay without an air pump.

However, you’ll need to pay attention to your fish and watch for any of these signs, which mean your fish need more oxygen:

  • They’re gulping down air from the surface of the tank
  • Their gills are moving faster than normal
  • Your fish aren’t very active in general

Do Oscar Fish Need a Heater?

fish tank heater

Yes, Oscar fish need a heater to mimic the tropical climates they’re native to. Your tank should be between 74 and 81 degrees Fahrenheit, with 77 being ideal. A heater can keep the temperature stable, which makes your fish healthier.

But heat isn’t the only parameter you’ll need to keep an eye on. The pH level should always be between 6 and 7.5. Test the tank water’s pH regularly to cut down on nitrates and nitrites, as these are toxic to fish at high levels.

Finally, changing out 10-15% of the tank water every week will also help keep conditions ideal for your Oscar fish.

What Tank Setup Do You Need for Oscar Fish?

Here’s your complete shopping list for the perfect Oscar fish tank setup:

  • A big enough tank. You can technically get away with an Oscar fish tank size of 55 gallons, but you’ll have no room for any other tank mates. A 75-gallon tank gives you far more flexibility over your fish’s long lifespan.
  • An aquarium hood or lid. This is a crucial element of Oscar fish care because they’re known to jump. Many tanks come standard with one. If yours doesn’t, be sure to measure your tank and choose a lid with matching dimensions.
  • A shatter-proof heater and tank thermometer. Oscars love to play rough. That can include headbutting your tank heater. So, a shatter-proof option and a separate thermometer are the safest options for these feisty fish.
  • Plants and décor to help your Oscar feel safe. Oscars aren’t shy, but they like having hiding spots in their tank. These fish also tend to rearrange, so the décor provides them with a fun activity. Don’t forget to consider the average Oscar fish size—tunnels and caves will need to be fairly large.
  • Lighting to support any live plants and show off your fish. Plants need 10-12 hours of light per day. Oscars themselves don’t particularly mind whether their tank is dark or lit up.
  • A coarse sand or gravel substrate. We prefer gravel in an Oscar fish tank for two reasons. First, it won’t clog your filter like sand can. It’s also much easier for live aquarium plants to take root in gravel.
  • A high-quality, powerful filter with spray bar. You need both of these to effectively remove your Oscar’s waste and keep the water oxygenated.
  • Test kits to check your water parameters. Large amounts of waste are unavoidable with Oscars since they’re so big. You’ll need to test pH, nitrites, nitrates, and ammonia regularly.
  • Food suitable for Oscars’ carnivorous diets. Live food like crickets or mealworms also make great treats now and then. For baby Oscars, try frozen bloodworms.

Oscar Fish Tank Size and Setup: The Bottom Line

What all this boils down to is that Oscar fish care isn’t the easiest thing to manage. Compared to other cichlids, Oscars are famous for being messy and needing more frequent water changes. And the smaller your tank, the more closely you’ll have to watch your water parameters.

But Oscars are also very rewarding fish to keep thanks to their long lifespan, unique personalities, and beautiful appearance.

So long as you take the time for proper Oscar fish tank setup and maintenance, you should be able to enjoy your fishy friend’s company for around 10—or even up to 20—years.

About the Author

Oscar cichlid fish

Dustin Williams

Dustin Williams is a seasoned author who brings a wealth of knowledge and experience to the world of pet literature. His expertise stems from a lifelong immersion in the fascinating world of animal companionship and care. As a third-generation aquarist, Mr. Williams boasts a deep understanding of aquatic life. His passion began in childhood and [...] Author Details

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