Oscar Fish: Ultimate Guide (Care, Diet, Breeding & More)

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Written By Matt Stevens

Hi, I'm Matt! I've been obsessed with fishkeeping for over 15 years now and created this site to share my knowledge with others.

The Oscar Fish is known to be one of the most attractive and majestic freshwater fish. This explains why it’s a highly popular choice for aquariums as well.

The way they trot around the aquarium makes for a wonderful sight, but Oscar Fish are also known to be quite aggressive, which is why you need to know everything you can about owning and taking care of them before committing to buying one.

You don’t have to worry at all because we have come up with this incredibly helpful guide so you can learn all about caring for your Oscar Fish. This includes looking after their habitat and water requirements, diet, tank mates, breeding, and much more.

Species Overview

The Oscar Fish is a species of fish from the cichlid family and is given the scientific name Astronotus ocellatus. They are also called the velvet cichlid, marble cichlid, and tiger Oscar. These names vary according to the appearance of the fish.

Oscar Fish are native to the freshwaters of South America, including Brazil, Columbia, Ecuador, Peru, French Guiana, and several other countries. They are also found in abundance in the Amazon River basin since they prefer to inhabit passive waters with rocks and debris.

Oscar Fish have also been found in smaller numbers in countries like Australia, China, and the state of Florida. This is due to the escaping of fish during transit, as well as being released into the water by owners who can’t look after them properly.

Life SpanUp to 20 Years
Colour FormVarious
Care levelModerate
CompatibilityLarge, passive fish
Size12 to 15 Inches
Tank SetupFreshwater: rocks and caves
Minimum Tank Size55 Gallons

Oscars have a striking and attractive appearance, which makes them an obvious choice for aquariums. However, their aggressive temperament can cause a bit of a problem, especially if they are made to cohabitate with other fish species.

This is one reason beginners are advised not to keep Oscar Fish in their aquarium or add them to an aquarium with other species. They require certain arrangements and aquarium settings to live peacefully.

Another reason why Oscar Fish require different arrangements is that they can grow up to 12 inches in an aquarium. If left in the wild, they can grow up to 15 inches during the first year.


On average, Oscar Fish can live anywhere between 10 to 13 years. However, if you take good care of them, they can also surpass the 15-year milestone. Their lifespan is quite impressive compared to other species and is another reason for their popularity in the aquarium community.

Plus, caring for Oscars over a long period will help develop a bond between you and your pet fish. Therefore, if you want to keep an Oscar Fish and ensure that they live a long and healthy life, you will have to maintain proper living conditions for them and look after their diet as well.


Oscar Fish can differ in appearance, depending on their type, but they do share some similar features, like a long and rounded body shape. Their caudal fins are symmetrical like other cichlids, and their dorsal fins and anal fins also extend up to the caudal fins.

Red Tiger Oscar Fish.
Red Tiger Oscar Fish.

The fins give Oscar Fish a burly look. Moreover, they have large eyes and a neutral-colored patch of skin that runs down till their dorsal fins.

Young Oscars have a different color from the adult ones, so it’ll be a pleasant sight watching them change color over time.

Types of Oscar Fish

There are several types of Oscar Fish, and each of them has different appearances and characteristics. Let’s have a look at the most common types of Oscars you can find for your aquarium.

1.     Tiger Oscar Fish

The tiger Oscar Fish has the most common appearance among all of the Oscars you see, and they have an orange and black color combination. Basically, their body is black with orange lines, as well as colored spots all over the body. Most of their body is colorless between the lips to the dorsal fins.

2.     Black Oscar Fish

Black Oscar Fish is a newer species, and they have a combination of grey and black colors. They have a unique pattern that also gives them stealth in the water. They look different from the other species because they have no bright-colored spots or lines on their body.

3.     Red Oscar Fish

The Red Oscar Fish is mostly red with very few patterns. Plus, they don’t have any coloring on their fins, and the red color is visible along their sides.

4.     Albino Oscar Fish

A unique type of Oscar Fish is the Albino Oscar Fish. They have a light-colored body without any patterns, but they do have red-colored spots scattered across their sides. Their fins are also colorless.

5.     Lemon Oscar Fish

The Lemon Oscar Fish has a similar body to the Red Oscar Fish, but it has more of a lemon-yellow color instead of red spots.


In their first year, Oscar Fish can grow anywhere between 10-12 inches with an average of 1 inch per month. If you leave them in freshwater streams, they can even grow up to 15 inches long.

This also tells you that you need to provide Oscar Fish with adequate space to grow during their first year. Otherwise, you risk hindering their growth.

Oscar Fish Care

If you are fascinated by Oscar Fish and are considering keeping them in your aquarium, there is a lot you have to learn. Oscar Fish require a lot more care than several other species of fish, and they require an environment that feels closer to their natural habitat.

Astronotus ocellatus in the zoo.

Although the fish themselves don’t need a lot of care, you have to take care of several factors regarding their wellbeing, such as the tank size and condition.

Let’s begin by discussing the tank size that you need to have in order to raise Oscar Fish safely.

Tank Size

Ideally, your Oscar Fish tank should have at least a 55-gallon capacity since they are larger in size and need extra space to grow and live properly.

If you want to own more than one Oscar Fish, then you should add 25 gallons for each fish. So if you have two Oscars, you need an 80-gallon tank, and for three, you need 105 gallons.

If you fail to provide sufficient space for your Oscar Fish, they risk exposing them to a lot of stress and hindering their growth. Moreover, it will make them more aggressive, which can prevent them from living peacefully in the aquarium.

Since many people buy Oscar Fish when they are 1 to 3 months old, it is important to remember that they will grow too. Some people make the mistake of sizing their tanks according to the initial growth of the Oscar fish, which can disturb its growth patterns.

Water Parameters

Another factor that you must consider is how you keep the water parameters. These should align with recommended levels. Maintaining the water conditions is important to improve your Oscar Fish’s lifespan and health.

Firstly, the water temperature needs to be controlled between 75-80°F, and the pH levels should be between 6 and 8. Last but not least, the water hardness has to be between 12 and 15dH.

You may think that filtration and lighting are an important part of caring for your Oscar Fish, but they aren’t as significant as the ones we have mentioned above. Plus, you don’t have to install a pump to produce a current in the water.

All you need to do is to keep the water parameters right since changing water levels or conditions can also affect the health of your Oscar Fish.

Tiger Oscar Fish swimming in an aquarium.
Tiger Oscar Fish.

What to Put In Their Tank?

Although the tank size and water parameters are the crucial factors, it doesn’t mean that you should leave your aquarium empty. Not only will setting up the tank make it look beautiful, but it will also aid in keeping the fish healthy and happy.

Firstly, you should consider setting up hiding places in the aquarium so your Oscars have a safe space. Since they are used to rocks and debris, you can place rocks and driftwood inside the tank.

You can also add plants to the aquarium, but since Oscars like to dig, it is wise to have floating ones, like Hornwort. These plants will continue to grow properly without suffering from damage.

Also, because Oscars like to dig and explore the substrate, you will have to ensure that you add something soft to the bottom layer. Apart from this, Oscar owners can make do with standard aquarium lighting too.

However, since they need a lot of space to move around, you don’t need to add a lot of decorations inside the tank.

Common Diseases

If you are going to keep an Oscar Fish in your home aquarium, you need to be aware of common diseases that they may encounter, such as Hole in the Head disease. It causes one or two holes in the head of an Oscar Fish and can leave a scar if not treated properly.

The main cause of Hole in the Head disease is a parasite called Hexamita, and it can also mean that your Oscar is undernourished.

To prevent and cure Hole in the Head disease, you have to maintain the water quality inside the aquarium. However, if you notice your fish suffering from the disease, test your water and change it if anything seems to be wrong.

Moreover, you should alter their diet and add more nutrients to it since it will improve their immune system. If things still don’t get better, you may have to administer medication, such as Flagyl or Metronidazole, but only if prescribed by the veterinary doctor.

What Do Oscar Fish Eat?

When it comes to feeding your Oscar Fish, there are several options that you can choose from. Since they are omnivores, Oscars won’t be fussy about what you feed them.

However, it is very important to provide them with a good dose of proteins, which can reduce the likelihood of developing any diseases. You should feed them white worms and high-protein flakes to nourish them with proteins.

You can add pellets to the tank if you wish, and if your Oscar Fish are now adults, they can also digest live and processed food, such as shrimps, bloodworms, crickets, insects.

Aquatic experts also suggest feeding your Oscar Fish fruits and nuts, but in a carefully moderated quantity. Frozen peas are also known to be helpful in enhancing the color of your fish’s body.

How frequently you feed them also impacts their growth. Baby Oscar Fish require feeding twice or thrice, while adults only need feeding every one or two days.

Behavior & Temperament

Oscar Fish have quite an unpredictable behavior that is often misunderstood. Since they have a reputation for being aggressive, aquarium owners tend to steer clear of Oscar Fish and consider them to be mean.

Oscars can be aggressive and don’t like other fish cohabitating with them, but they only behave this way if they have to compete with other fish. For instance, if they are kept in a crowded tank or forced to coexist with other species, Oscar Fish will naturally act out.

So, as long as you maintain proper conditions for them, they will keep living comfortably. Another thing you might notice with Oscar Fish is that they explore the substrate for any food leftovers, so don’t be worried if you see them at the bottom or middle of the tank.

To find out more about their behavior, check out this video.

Oscar Fish Tank Mates

As mentioned above, Oscar Fish don’t like to live in crowded or small tanks where they have to live with other species. Therefore, it can be quite difficult to find tank mates for them since they are aggressive and territorial.

It is important to note that Oscars do cohabitate with other species in their natural habitat, so they aren’t as aggressive as they become inside an aquarium.

To ensure that your Oscars don’t attack other fish, you should place larger fish that aren’t intimidated, preferably from the cichlids family.

When it comes to considering what fish go with Oscar Fish, there are a few options to choose from. These include:

Ideally, the best companions for Oscar Fish are Oscar Fish themselves. If you choose to pair them with fish of another species, things may get difficult, no matter how large your tank is.

Generally, you should have fish that are as large as Oscar Fish, but not as aggressive as them.

Apart from the aforementioned options, you can also go with the Silver dollar, Arowanas, Chocolate cichlids, Demon earth eaters, and several others. Whenever you introduce your Oscars to new species, you will have to keep monitoring the tank to see how they get along.


If you think Oscar Fish are difficult to take care of, you may find it even more difficult to breed them. There is a lot of experience required to do so, mainly because Oscars are very selective of their mating partners.

To navigate around this issue, you should look for mated pairs of Oscar Fish when you buy them for your aquarium. Moreover, Oscars prefer the rainy season for breeding, which is why you can lower the temperature by 2-3 degrees and partially change the water every few days.

Another method you can try is to sprinkle water on the surface of the tank for a few minutes every day, as this would encourage them to mate.

A noticeable sign that Oscars are ready to mate is that they shake their fins more, and their gills are flared as well. This is a sign that the female fish is ready to lay eggs, which can amount to up to 3000 easily.

When the female lays its eggs, the pair continues to swim around them until they are ready to hatch. Female Oscars also have a habit of clearing the substrate to create a safe environment for the eggs.

Once the eggs start to hatch after two or three days, you may have to shift them to another tank and look after their growth and wellbeing.

Make sure you have a large enough tank to accommodate all of the Oscar Fish once they start growing since they grow by one or two inches every month.

Final Thoughts

By now, you have complete knowledge about how to care for Oscar Fish, including their water requirements, diet, diseases, breeding, and much more.

The important thing to remember is that you can’t simply buy Oscars and put them in your existing fish tank. Rather, you will have to consider the tank size, water conditions, and also the tank mates before you even consider buying this species.

No doubt, it can be quite difficult and challenging to take care of Oscar Fish, but the whole experience can be quite rewarding. Once you get the hang of it, you will be able to add their care to your daily routine.