Oscar Fish Care Guide

If you’re looking for a spunky and impressive freshwater fish, you’ve probably considered getting an Oscar. Oscars are well-known fish, even among people who aren’t fish people. It’s hard not to fall in love with their buggy eyes and curious nature.

And, fortunately, Oscar care isn’t so difficult.

If you want to keep an Oscar and you have some questions about their care, you’ve come to the right place! Read along to get a comprehensive review of how to care for Oscars. 

All About Oscar Fish

Technically in the Cichlid family, Oscars hail from South American River basins in Peru, Ecuador, Brazil, and Columbia. They reach up to eighteen inches at maturity and they can do it surprisingly quickly. They can grow as much as an inch in one month! 

Behavior & Temperament

Oscars are not known for their sweet temperaments. These feisty freshwater fish are territorial in nature. They need large tanks, and often don’t do well in community settings. 

Your Oscar will need a 75 gallon aquarium as an absolute minimum with no additional tankmates. Due to their aggressive nature, there should be no tankmates that can fit in its mouth. Ideally, they should only be housed with other South American Cichlids that are larger in size. 

Despite Oscars’ rough-around-the-edges temperament, they are responsive and rewarding fish to keep. 

Additionally, you should also keep a lid on your Oscar’s aquarium. Oscars tend to jump out of their aquarium to explore their surroundings. 

They’re particularly prone to jumping out of tanks during feeding times. Anyone who has kept an Oscar can tell you these are some hungry fish!

How to Care for Oscar Fish


Oscars aren’t picky when it comes to food. They’re very willing to eat their tankmates if they happen to be mouth-sized, so keep that in mind! 

Fortunately, though, Oscars are easy to feed. Cichlid Pellets can make up most of their diet. To spice up their diet, you can also feed them crickets, feeder fish, mealworms, and locusts. Yum! 

Oscars always seem hungry. They often pace their tank and follow passersby, hoping for an extra meal. Sometimes finding a balance for feeding time is hard. 

Feed your Oscar twice a day and monitor how much food they can eat in a minute. Afterward, make sure to remove excess food. If you feel like they might still be overeating, monitor your water quality. Overfeeding will raise your nitrates considerably and can be harmful to your fish.

How long do they live?

Oscars live 10-13 years on average. So they’re a real commitment! Similar to getting a dog in some ways.

Different Types of Oscar Fish

The main three types of Oscars are: Red Oscars, Tiger Oscars, and Albino Oscars. 

However, a wide variety of unusual Oscars are available through selective breeding. There are Black Oscars, White Oscars, Lemon Oscars, Green Oscars, Blue Oscars, Veil Tail Oscars, and even a Florida Oscar.

Setting up your Oscar Fish Tank

Let’s go over some of the specific requirements that you need to cover in order to set up your Oscar fish tank.

Aquarium size

Your Oscar will need a minimum of a 75-gallon tank. Oscars are large fish and they enjoy having room to swim. They also produce a heavy bioload (essentially waste), which means they need extra water to help with water quality. 

If you want to keep two Oscars, we suggest a 120-gallon tank or more. The same goes for adding non-Oscar tankmates, the more tankmates you have, the more room you need.

You can start them off in a smaller tank, but keep in mind that they’ll quickly outgrow it.

Remember, the larger the tank, the better your fish’s quality of life. 

Oscar Fish for Home Tank

Type of Substrate

Oscars like to rearrange their furniture. If you watch your Oscar, you will notice them rearranging decorations and even the pebbles in their substrate. 

Both sand and gravel are an adequate substrate for Oscars. I prefer the larger rock pieces since Oscars like to put their substrate in their mouths and spit it back out! 

Only a minimum substrate is necessary; the substrate layer can be anywhere from 1-2 inches. 


Oscars are high waste producers, make sure to provide ample filtration, and check your water quality regularly. There’s not a one-size-fits-all for aquarium filtration. If you look into the subject of aquarium filtration, people tend to have different preferences. 

There are many different filters on the market. I recommend a canister filter or a large overhead filter. Oscars require excellent filtration, so make sure that you pick a proper filter. 

Another good option is an aquarium sump. An aquarium sump allows you to add different filtrations outside of the tank. A sump also allows you to conceal most of your aquarium filtration.

There are three types of filtration you should keep in your aquarium: 

  • Biological
  • Mechanical
  • Chemical

Mechanical filtration can come in the form of filter sponges or the standard cartridges that come with your filter. The mechanical filtration removes large debris and food from your tank. 

Biological filtration will prevent your tank from cycling. Think of biological filtration as anything that will adequately hold bacteria, for example, lava rocks, substrate, eco stone, and decorations. Biological filtration is particularly important with high waste producers because the high amount of waste makes you more susceptible to new tank cycling. 

Chemical filtration is different filter media designed to remove impurities from the water. I highly suggest using activated carbon or high capacity GFO as a form of chemical filtration in your tank. 

When adding carbon or GFO to your tank, make sure you rinse it thoroughly and use the proper amount listed on the product. If using activated carbon, I would also suggest purchasing a phosban reactor. 

The reactor prevents carbon from leaching, which causes spikes in phosphates. Leached carbon leads to unwanted algal blooms!


Compared to most fish, Oscars do not have particular lighting requirements. Overall, Oscars prefer low lighting. 

If you want to help your energy bill opt for an LED light. LEDs have two additional bonuses, as well. They won’t add extra heat to your aquarium and Oscar colors really pop under LEDs! 

Freshwater Oscar Fish

Plants and Decorations

Your Oscar loves to move his decorations around; it’s a lot of fun to watch! The main takeaway, though, is do not put anything that will be easy to break in the tank. 

Your Oscar could potentially destroy your tank and/or hurt themselves.

Tank decorations can be weighted down to prevent your fish from moving them, such as fake plants. 

Real plants can work. However, keep in mind that your plants run the risk of being destroyed so I wouldn’t buy anything too expensive or grow too attached. 

Driftwood is an excellent addition to your tank. Not only is it similar to an Oscar’s natural environment, but driftwood helps lower the pH of the tank and keep their water soft. 

If you decide to keep driftwood in your tank, you may want to boil it several times before introducing it to the tank. Treating your driftwood is helpful if you do not want to release tannins into your aquarium. Tannins are not harmful to your aquarium or Oscar, but they will turn your aquarium water to a dark brown. 

Essentially, just boil it as many times as it takes for the water to stop turning brown. Once you boil it and the water remains clear, you should be good to go. 

If you’re looking for enrichment for your Oscar, you can put easily movable pieces of décor in the aquarium. Make sure anything you give them is not small enough to be swallowed though and ensure that it’s aquarium safe. 

Tank Environment for Oscars

Water Temperature

74-81 degrees Fahrenheit 

Water Flow

Ideally, there should be a heavy water flow in your Oscar’s aquarium. Generally, the higher the flow, the better. Oscars enjoy surfing and will do well with a water turnover rate of 4-12 times per hour. 

pH, Acidity & Alkalinity Levels

Oscars have a large range of tolerance when it comes to pH. Freshwater fish prefer acidic water, but Oscars prefer a range from 6.8-7.4. Oscars are even known to tolerate pH between 6.0-7.8.

Even though Oscars have a wide pH tolerance, they will not tolerate large swings in pH. Make sure to be careful when adding fish and be prepared to adjust for pH if necessary. 

If your pH is too high you can add almond leaves or driftwood to your tank as a simple remedy. 

If your pH is too low, you can add small amounts of baking soda. Start with 1 tsp per gallon, until you reach your desired pH. 

You can also buy additives to help raise the pH at your local pet store. 

You will find a low amount of alkalinity, if not none, in your freshwater tank. Alkalinity is a buffer for swings in pH. Alkalinity can be added to the tank in a powdered form. Make sure anything you purchase to increase alkalinity will not also increase your pH. 

Chlorine and Chloramines

Tap water has ions and heavy metals that are not appropriate for aquarium fish water. 

Fortunately, there are plenty of options for keeping your water safe for your Oscar. One of the most common options is to use a water conditioner, which removes the chlorine and chloramines from your aquarium. 

Two other options are to purchase an Reverse Osmosis (RO) or Deionized (DI) unit to make safe water for aquariums. You can also buy RO or aquarium safe water at your local pet store. 

Ammonia, Nitrite, and Nitrate

Ideally, there should be no ammonia or nitrite in the tank. When there are even trace amounts of these molecules in your aquarium, you run the risk of stressing your fish and ultimately killing your Oscar. 

To prevent ammonia or nitrite, make sure to cycle your tank. Regular tank maintenance, such as water changes and cleaning mechanical filtration, helps to prevent ammonia and nitrites after a tank cycle. 

If you notice trace amounts of either nitrite or ammonia, perform a water change and add some natural biological booster to your tank. The biological booster will help speed up the new cycling to keep your water safe for your Oscar. 

When you first get an Oscar and perform your water quality tests, you will find that your nitrates are much higher than you would have imagined. 

No harm! It’s best to keep nitrates under 20ppm, but at 40ppm, you still have time and plenty of opportunities to lower your nitrates. These high numbers are due to their large appetites and since they produce a substantial amount of waste. 

To prevent nitrate buildup, do a 25% water change once a week and regularly change or clean any mechanical filtration you have. If nitrates are still climbing in your tank considering either cutting back on food or doing two 25% water changes per week. 

Another option to reduce nitrates is to add a protein skimmer. Protein skimmers work best when they are in the sump, but protein skimmers that hang over the side of the aquarium are also available. 

Oscar Fish

Common Challenges with Oscars

Diseases and Treatments

Hole in the Head Disease

The symptoms of this disease are exactly what you’d expect, your Oscar will have small to large divets in its Head. Hole in Head is a parasitic infection caused by the parasite Hexamia. 

If you feel your fish is in the early stages of Hole in the Head, check your water parameters to make sure there are no significant fluctuations. Often times, Hole in the Head disease is caused by poor water quality. 

Another possible culprit is the diet for your Oscar. Feeder fish often carry ich and can leave your tank susceptible to bacterial infections. If you notice signs of bacteria in the tank (cloudy eyes, spots on fins, etc.) treat your fish in a quarantine tank for bacteria. 

Hole in the Head can also be brought on by a poor diet as well. Make sure your Oscar gets a variety of foods and is fed a proper diet for their species. 

When keeping any fish, it’s best practice to have an active quarantine tank where you can administer medications. Your quarantine tank should be set up similarly to the first tank and should be in use for the duration of the treatment.

The best way to treat Hole in the Head is to prevent it. In the early stages of the disease, you can correct water quality parameters and allow your fish to heal. 

If the disease has progressed, make sure to quarantine your Oscar and administer both anti-parasitic and anti-bacterial solutions to your fish. There are plenty of options in both categories at your local pet store. 

When your fish has recovered, there will be scarring from the disease. A helpful suggestion is to take a picture so that if you can be sure if there are new marks if you believe there is a future outbreak. 


Ich is not a disease that plagues only cichlids. Ich is the stuff of nightmare for hobbyists, but it can be controlled. Prevention is critical in creating an Ich free tank!

Ich is a parasite that is often present in aquariums, but it doesn’t expose itself until there are unstable water conditions. It will look like small white spots surrounding the entirety of your fish. The key is to catch ich fast, with early warning signs being as simple as fish rubbing against their décor. 

Regularly check your water quality and quarantine any live animals that are entering your system. Everyone has their own arrangements for quarantine. Some allow for a three-day quarantine, while others plan for an entire month. Generally, the more money/time/love you’ve spent on your tank, the longer you’ll want to quarantine. 

If your aquarium does not have plants, add some aquarium salt in your sump or filter. Aquarium salt works well for the prevention of ich, especially when used in conjunction with proper diet and tank maintenance. 

Isolate any fish you have with ich and treat them with a parasitic medication and a bacterial and fungal medication. The combined treatments help prevents future complications that often follow ich. Make sure to keep the stress low on your fish during this time. 

In the main tank, you can raise the temperature to at least the 80 degrees Fahrenheit and allow the tank to sit for at least one week. Make sure to set parameters back to normal for your Oscar before reintroducing them to the aquarium. 

Fin and Tail Rot

Fin and Tail Rot is a bacterial infection. The signs are apparent to the name. Your Oscar will have torn, bloody, or darkened fins. 

This disease is due to issues with water quality, stress, and overcrowding. Check your water quality parameters and consider upsizing your tank or rehoming fish if crowding appears to be an issue. 

Treat with a bacterial medication and improved aquarium conditions. 

Popeye Disease

Yikes, this one is gross! Once again, an aptly-named disease, your Oscar will typically have one eye-popping out of its socket, usually hazy or discolored. 

Popeye is typically brought on by poor water conditions. Check all the water parameters and get them back into an acceptable range. 

Chances are good that your fish will lose their eye, even if caught early and properly treated. Popeye does not happen unless water quality conditions continue in a poor state for too long. The best prevention for Popeye is to make sure that your aquarium is maintained correctly. 


Septicemia is a bacterial infection that often occurs because of an injury that develops into a disease. Make sure that your tank is safe for your Oscar, with no pointy blunt objects. Aggressive tankmates may also be a culprit.

Treat with an antibiotic regimen in a quarantine aquarium, and make sure that water conditions are ideal before reintroducing your Oscar. 

Cycling Your Oscar Tank

Ammonia Poisoning

It’s easy for your Oscar’s aquarium to develop ammonia. If the tank is new, if there was a large addition of fish, or if you didn’t perform water changes for a considerable amount of time; your Oscar might be suffering from ammonia poisoning. The most common symptom is fish gasping at the surface of the water and/or a lack of appetite. 

If your fish is exhibiting symptoms and your ammonia is reading high, do a 50% water change. Add biological booster when refilling the water. Then, continue to perform significant water changes with booster every other day until the ammonia is no longer present (or reading negligible) in the tank. 

Excessive Nitrates

Nitrates can climb quickly in a cichlid tank. Nitrates will not kill your fish immediately but they could if allowed to continue long-term.

The only way to prevent excessive nitrates is to do regular water changes and keep up with maintenance on filtration systems. Fish will often stop eating and might experience a loss of color when excessive nitrates are in their aquarium. 

If nitrates are high, be careful performing substantial water changes, this could shock your fish. Perform a 25% water change two to three times a week until the nitrates are at least under 40ppm. If you are performing 25% water changes twice a week and your nitrates are still high, consider lightening up the bioload on your aquarium by reducing food or the amount of fish. 

Oscar Fish Aquarium


How do you prevent Oscars from jumping out of the tank? 

The best way to prevent Oscars from jumping out of your tank is to have a well-fitted lid on the tank. 

What are suitable tank mates for Oscars?

Your Oscar does not make the best tankmate; that said, they are capable of being housed with other species of African Cichlids and even other Oscars. If you decide just to get one Oscar, don’t worry, unlike community fish, your Oscar can live a healthy, happy life without an aquarium friend. 

Make sure to provide ample room for if you do add more fish. Your Oscar is more likely to be agreeable with his new tank mate if there is plenty of room for both him and his tankmate!

When adding a fish to your tank, make sure you feed your current fish before introducing the new tankmate. Another good trick is to rearrange the decorations right before introducing a new fish to the tank. 

And definitely do not buy a fish that could fit in your Oscar’s mouth; you won’t have that fish for long! 

Final Word

Oscars are excellent aquarium residents for both beginners and pros. Their bright colors and interesting personalities make them truly special.

They can come with their fair share of challenges, such as large tank sizes and heavy filtration needs. But take the extra time to get everything set up properly and set yourself up for success with these amazing cichlids! 

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