Oscar Care Guide: Diet, Tank Mates, Diseases, Breeding & More

Updated: December 17, 2022

The Oscar is a beautiful and popular freshwater fish that is easy to care for and makes a great addition to any aquarium.

This guide will teach you everything you need to know about Oscar care, including their diet, size, tank mates, and more!

Species overview

Oscars (Astronotus ocellatus) are a type of cichlid that is native to South America, specifically the Amazon Basin. They can be found in countries like Peru, Brazil, and Columbia.

Oscars are one of the most popular aquarium fish for a variety of reasons. They are relatively easy to care for, are very tolerant of a wide range of water conditions, and are incredibly interesting to watch. They are also a very hardy fish, which means they are less likely to succumb to disease.

Despite their popularity, Oscars can be very aggressive fish. They are known to fight with one another and other tank mates, so it’s important to be careful when choosing what to put in their tank.

Oscars are a very large fish, so they will need a tank that is at least 50 gallons. They are also very messy eaters, so a good filtration system is a must.



The Oscar is a freshwater fish that is easily recognizable due to their unique shape and coloration.

These fish have a very stout body that is shaped like an oval. They have a large head with a protruding lower jaw. This jaw is lined with small, sharp teeth.

The fins on an Oscar are large and rounded. The dorsal fin is located towards the middle of the fish’s back. The anal fin is located towards the back of the fish, just before the caudal fin. The caudal fin is forked and has a rounded shape.

The body of an Oscar is covered in large scales. The color of these fish can vary greatly, but they are typically some shade of brown or orange. Some Oscars may have black spots on their body.


Oscars have an average lifespan of 10-12 years. However, with the proper care, they can live up to 20 years. The main factor that determines an Oscar’s lifespan is their environment.

If they are kept in a cramped tank with poor water quality, they will not live nearly as long as they would in a spacious, well-maintained aquarium.


Oscars can grow to be about a foot long, and they can live for up to 15 years with proper care. They are one of the larger freshwater aquarium fish, so they need a lot of space to swim and plenty of hiding places.


Tank Size

The recommended tank size for keeping Oscars is 55 gallons. If you want to keep more than one fish, you’ll need to increase the size of your tank accordingly.

For every extra fish you want to keep, add an additional 30 to 40 gallons to your tank.

Water Parameters

The Oscar is a freshwater fish that is native to South America. They are typically found in rivers, but they can also be found in lakes and floodplains.

The water in their natural habitat is typically warm with a pH level between 6.5 and 7.5. The hardness of the water is usually between 2 and 12 dGH.

When keeping Oscars in captivity, it is important to maintain water conditions that closely resemble their natural habitat.

The water temperature should be kept between 72 and 80 degrees Fahrenheit. The pH level should be between 6.5 and 7.5. The hardness of the water should be between 2 and 12 dGH.

It is also important to maintain a high level of dissolved oxygen in the water. Oscars are known to be surface feeders, so they need access to oxygen-rich water.

What To Put In Their Tank

When setting up an aquarium for Oscars it’s important to remember that these fish can get quite large. That being the case, you need to make sure you have a tank that can accommodate them when they reach full size.

The inside of their tank should have plenty of hiding spots and places to explore. Driftwood, rocks, and caves are all great options. You can even use live plants if you want (just be aware that they might nibble on them).

The substrate you choose is also important. Oscars are known to dig around a bit so you’ll want something that can stand up to that. We recommend using a heavier gravel since it won’t get moved around as easily.

You should also include a filter in their tank. Oscars are messy eaters and produce a lot of waste. A good filter will help to keep the water quality high and prevent any issues down the road.

Common Diseases

The Oscar is a very hardy fish, but that doesn’t mean they can’t get sick. In fact, there are a few diseases that these fish are particularly susceptible to.

The most common illness that Oscars get is ich. This is a parasites that infects the fish and can be quite serious if left untreated.

The symptoms of ich include white spots on the body, gills, and fins of the fish. If you notice these symptoms, it’s important to act fast and begin treatment immediately.

Another disease that Oscars are prone to is hole-in-the-head disease. This is another parasites that affects the fish, and it’s characterized by pits or holes in the head of the fish.

This disease is also curable, but it’s important to act fast. The longer you wait, the more severe the disease will become and the harder it will be to treat.

The best way to prevent these diseases is to maintain clean and stable water conditions in the tank. A healthy environment will go a long way in keeping your Oscar fish happy and healthy.

Behavior & Temperament

Oscars are one of the most popular freshwater fish for a reason—they’re big, they’re beautiful, and they’re relatively easy to care for.

Oscars are also known to be one of the more aggressive freshwater fish. They are known to attack other fish, plants, and even inanimate objects that they see as a threat. So, if you’re thinking about getting an Oscar, it’s important to do your research first.

Although they can be aggressive, Oscars are also known to be very intelligent. They have been known to learn tricks and even come when they are called.

Oscars are also a very active fish. They need a lot of space to swim and explore. A 20-gallon tank is the minimum size you should get for an Oscar, but a larger tank is always better.

Oscars are also a very messy fish. They produce a lot of waste, so you need to be prepared to do a lot of cleaning.

Tank Mates

When it comes to Oscar tank mates, there are a few things to keep in mind. First, these fish can reach a whopping size of 18 inches. That’s big enough to make even the most docile fish think twice about messing with them.

As a result, you need to choose tank mates that are either too large to be eaten or too small to be seen as a threat.

Cichlids are a popular choice since they come in a wide range of sizes and personalities. Some good Oscar tank mates include:

Of course, this is just a small sampling of compatible species. There are plenty of other fish that would make good tank mates for Oscars.

The most important thing is to do your research and make sure that any potential tank mates can thrive in the same water conditions.


A lot of people assume that it’s impossible to breed Oscars in captivity. That’s not true! It is possible, but it’s definitely not easy.

The first step is to find a pair of Oscars that are willing to breed. This can be tricky because they’re not necessarily social creatures. If you’re keeping them in a tank with other fish, they may not breed.

The next step is to set up a breeding tank. It should be at least 55 gallons. The water should be soft and acidic, with a pH of around 6.5. The temperature should be between 78 and 82 degrees Fahrenheit.

You’ll also need to add some plants and hiding places. Oscars like to lay their eggs in secluded areas.

Once the tank is set up, it’s time to add the Oscars. If everything goes according to plan, they will start to breed. The female will lay around 2,000 eggs, which the male will then fertilize.

The eggs will hatch in about three days. The fry will be very small and vulnerable, so you’ll need to take care of them. Feed them live foods like brine shrimp and bloodworms.

As they grow, you can start to introduce them to pellets and flakes. Once they’re big enough, you can move them to a regular tank.


The Oscar is a beautiful and unique fish that is sure to add some excitement to your aquarium. They are relatively easy to care for but there are some things you need to be aware of before you get one.

Oscars are messy eaters and produce a lot of waste so you need to have a filter that can handle the load. They also grow to be quite large so you need to have a tank that can accommodate them.

If you’re looking for a fish that is a little bit different and a lot of fun, the Oscar is a great choice!