Oscar Fish – Species Profile & Facts

The Oscar Fish has the type of coloration and mixed patterns that are completely out of this world. They look amazing, no wonder so many fish enthusiasts want them in their aquarium. Each of them is a unique specimen that swims gracefully and might seem quite peaceful.

However, this couldn’t be farther from the truth. In fact, Oscars are well-known for their aggressive behavior that can make it difficult to keep them together with other fish. But don’t worry, we have it all figured out right here.

In this article, you are going to find out everything that a fish keeper needs to know about keeping Oscars at home. You will be able to set up a tank, set the correct water conditions and pick a few compatible tank mates as well.

Besides that, we are going to talk about the diet, the breeding process and where the Oscar Fish comes from. Firstly, let’s see what characterizes the natural habitat of this species!

Oscar Fish Natural Habitat

The Oscar Fish can be found in South America out in nature. There are plenty of them living in the Amazon River where many other interesting fishes can be found. There is nothing more diverse on the world than the Amazon and its surrounding areas when it comes to wildlife.

Thanks to the fishkeeping industry, now these beautiful Oscars are available worldwide. In the wild, they love to be around rocks and debris and prefer slow-moving waters. The hotspots where wild Oscars can be found are Colombia, Peru, Brazil, Ecuador and French Guiana.

In case you want to find this species by its scientific name, it is called Astronotus ocellatus.

Oscar Fish Fish Tank Requirements

When you start to set up your tank for your Oscar Fish, the first thing you need to do is to lay down some soft substrate. You are going to see them digging a lot and a they can hurt themselves with a rough substrate.

Make sure to fill the tank with plenty of rocks and bogwood if you want to make them feel at home. Since Oscars have their own territory, they also need some caves and other hiding places for shelter. They are quite big and tend to bump into decorations so those need to be fixed.

This applies to live plants as well, as they are root them up even if they are not going to eat them. Fortunately, there are some hardy plants to choose from. Our recommendation is to get some floating plants such as Hornwort.

Besides the decoration, you will need to fix all the equipment in the tank as well. They are big, powerful and willing to jump out of the tank if something is not right. You can prevent this by applying a lid to the top of the aquarium.

The bigger the tank, the better but it should be at least 55 gallons of size. A smaller tank will only cause them to be more aggressive towards their mates.

Oscar Fish Water Conditions

Oscars prefer slow-moving waters, as we mentioned before. This means that you need to buy a filter that generates some water flow and thus somewhat mimics their natural environment. The Amazon river itself and all the waters around it are pretty warm.

You can easily warm the water up by installing a good heater in your aquarium. The ideal temperature for the Oscar fish is 74 to 81 degrees Fahrenheit. The water acidity should be in the 6-8 pH range. As long as you keep the water conditions constant, your fish is going to be healthy and thriving.

When it comes to the lighting, it doesn’t need to be particularly dim or bright. Any aquarium lights will do the job with medium light. Now it depends on you whether you want a stronger water current in the tank or not. If so, you can either buy a water pump or invest into a stronger filter.

This also depends on the tank mates you keep in the aquarium, if there are any.

Oscar Fish Diet and Feeding

This is the part you are going to have the least issues with. The typical Oscar Fish diet is very simple. Since they are omnivorous, you can give them whatever fish food you want. The only thing you need to care about is to provide them enough vitamins and nutrition throughout the day.

In the Amazon, wild Oscars prefer to eat plants, small fish and larvae. There are so many fish foods available in the pet shop that contain those nutrients. They love to eat crustaceans and insects too. Their main foods in a home aquarium are usually flakes or pellets.

The ones they sell for cichlids contain all the nutrients they need in order to thrive. Their main protein source needs to be different types of frozen and live foods. The point of giving them live foods is to satisfy their natural hunting instincts.

They are constantly looking for food so it is a big excitement for them to hunt down some live foods. There is a wide range of fish foods that you can create at home and feed them. Feel free to cut some vegetables into little pieces and just throw them into the aquarium.

You need to keep their diet as diverse as possible and feed them 2-3 times each day. Give them the amount they can consume in a few minutes and collect the leftovers before they contaminate the water.

Oscar Fish Tank Mates

There is a reason why people call them River Dog or Dog Fish. They tend to be very aggressive and territorial so you need to be careful when choosing tank mates for them. The unusual and decorative look of this fish allows you to set up an exciting fish tank with only Oscars in it.

The reason why we suggest you to set up a single species tank is because it is the easiest way to keep Oscar Fish. They are simply too aggressive so it can be hard to find compatible tank mates. You can either buy a male and a female or a whole group of Oscars and they are going to have a great time.

They not only need a lot of space because of their size but they are very territorial as well. If you insist on setting up a community tank, then you should find some large and peaceful fish. And, of course, they will need a huge tank.

Our suggestions are Sailfin Plecos, Firemouth Cichlids, Jaguar Cichlids, Bichirs, Silver Dollars, Arowanas and Convict Cichlids. Cichlids are the best tank mates for the Oscar Fish in general. Avoid keeping any smaller fish or invertebrates because they are going to be eaten.

Oscar Fish Breeding

The Oscar Fish is definitely not easy to breed in captivity. The reason behind this is because they have some really high standards when it comes to picking mates. Buying a random male and a female Oscar and putting them in the same tank is probably not going to work.

The best way to go about it is to go to the pet shop and buy an established Oscar Fish pair. Or just buy a group of juveniles and wait until they grow up. Them spending time together and establishing a strong connection is only going to increase the chances of them breeding.

Now the problem with this is that it takes them 1-2 years until they become fertile. In the Amazon river, Oscars only breed during rainy season. You need to signal this somehow if you want them to breed. Set the temperature a few degrees lower and perform frequent water changes.

It has to be realistic, so you might need to sprinkle some water into the aquarium to make them think it’s indeed raining outside. The female and the male Oscar Fish will start to clean rock surfaces before breeding. Then, the female is going to lay down up to 3000 eggs there.

They defend this territory together for 2-3 days, until the eggs get hatched. If you take the fry and place them in a separate tank, they are going to be safe. You can do this by using a sponge filter. Then all you need to do is to make sure they eat 2 to 4 times every day.

The little Oscars will grow quickly so you might eventually need to put them into a bigger tank.


If you want to set up a single species tank, then the Oscar Fish is definitely one of the fish you need to consider. This species is very popular among fish keepers because of its unusual colors and patterns. Not to mention that they have a unique personality that will make you watch your aquarium for hours.

This fish is not the best idea for breeding nor for community tanks. You either need to be an experienced fish keeper or do quite a lot of research on the potential tank mates. This applies to the breeding process too. When it comes to feeding and tank setup, you are probably not going to have any issues.

avatar Noah
I’m Noah, chief editor at VIVO Pets and the proud owner of a playful, energetic husky (Max). I’ve been a volunteer at Rex Animal Rescue for over 2 years. I love learning and writing about different animals that can be kept as pets. read more...

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