Oscar Fish: Species Profile And Complete Care Guide

Oscar Fish (Astronotus Ocellatus)
Oscar Fish (Astronotus Ocellatus)
Dr. Mollie Newton
Published by Dr. Mollie Newton PHD| Senior Editor
Last updated: June 11, 2024
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In the realm of aquariums, the Oscar fish stands out as a prized species of freshwater fish, admired for its energetic personality. This trait might discourage some hobbyists from adding them to their tanks. However, we are ready to outline the pros and cons of owning Oscar fish in our comprehensive care guide.

Article Summary

  • Oscar fish (Astronotus ocellatus) are popular freshwater aquarium fish known for their feisty personalities and vibrant colors.
  • Common diseases that can affect Oscar fish include Ich, Hole in the head disease, Fin/tail rot, and Dropsy.
  • Oscars are monogamous, and breeding them requires pristine water conditions and a large tank to house the breeding pair and their offspring.

Species Overview

Common namesOscar fish, Oscars, velvet cichlid, red oscars, tiger oscar, marble cichlid, water dogs
Scientific nameAstronotus ocellatus
Size10-15 inches
Lifespan10-13 years
DistributionSouth America rivers
ColorRed, orange, yellow, dark green, brown
Minimum tank size75 gallons
Place in the tankBottom to Middle water column
Care levelModerate to advanced

History and Background

The oscar cichlid is native to the South American river basins, along with many other cichlid species.

What is an oscar fish?

An oscar is a tropical species that comes from the cichlid family and is a popular freshwater fish due to its large size and bright colors.


This large fish species hails from South America where they are mainly found in the Amazon River basin. They are now found in the wild in the southern United States, India, and Australia due to transplanting.

Natural Habitat

In their natural habitat this tropical fish enjoy shallow, slow moving waterways with tropical temperatures. Despite their large size they tend to prefer the bottom of the water column and enjoy sandy or muddy substrates.

What do Oscar fish taste like?

Unless you are raising your oscar fish in an aquaponics system with the intention to eat it, we don’t suggest reaching into your aquarium and plucking it out for dinner. However, some people do intentionally catch and raise oscars to eat, and many say that the flavor is similar to snappers. They do have white, flaky meat. But for most home aquarists, they’d rather think of their oscars as pet fish instead of food.


A Beautiful Oscar Fish In An Aquarium
A Beautiful Oscar Fish In An Aquarium

Due to their popularity there has been a wide variety of captive-bred oscars, bred in a rainbow of tropical colors.

What do Oscar fish look like?

Oscar fish are fairly flat and are 10 to 15 inches in size. Their fan-like fins generally have some outline or ornamentation displayed on them depending on the variety. They have pharyngeal jaws which means they have teeth set in their jaw as well as pharyngeal teeth. Oscars have a single nostril on each side of their snout and have ocelli at the base of the dorsal fin.

There are many varieties of this species that affect the colorations, markings, and fin length, but the wild types are generally dark green or brown in color with red, orange, and yellow markings.

Coloring can change with developmental phases and environmental factors…

Coloring can change with developmental phases and environmental factors such as poor water conditions. Proper oscar fish care and diet will lead to brighter, more vibrant coloring.

Types of Oscar fish

Albino Oscar Fish

With sparkly white scales albino oscar fish are surprisingly not solid white. In fact, you’ll notice orange and red designs along the bottom of their body that vary from fish to fish. The albino oscar is not due to environmental conditions, rather it is a genetic anomaly.

Tiger Oscar Fish

One of the most well known variants is the tiger oscar, easily identified by its black and orange pattern. Tiger oscars tend to have wild designs with spots of black or charcoal on their otherwise red bodies.

Black Tiger Oscar Fish

Black tiger oscars are a variation of the original tiger oscar and are mainly black with bright orange or red markings.

Red Oscar

An almost traditional looking oscar, the red oscar cichlid can be differentiated by their black and gray markings extending from the top of their head all the way to their tail, usually along the top of their body.

Lemon Oscar fish

The lemon oscar is often mistaken for an albino oscar as its coloration can vary from deep, mustard yellow, all the way to pale yellow.

Albino Red Oscar

There is a wide variety of albino oscars, easily seen in the albino red oscar. With a pale orange body some fish have a white face and spine while others have some subtle red-orange patches on their sides. Albino oscars can have eyes that are yellow, light red, or pink.

Black Oscar

Unlike many of the other oscar fish types mentioned above the black oscar coloring can occur naturally, and is closer to what the wild type looks like than most of the oscars we see today. Despite being called black oscars, there is still some orange and red coloring on this fish, it is just not as prominent.

How big do Oscar fish get?

A full grown oscar fish ranges from 10 to 15 inches in size and on average weigh about 3.5 lbs. Because of their size many people don’t keep them due to how large the oscar fish tank size requirements are. Females tend to be slightly smaller than males with an average size of 10 to 12 inches.

How fast do Oscar fish grow?

For the first year of their life oscars can grow roughly 1 inch per month in the right conditions. The fish reach sexual maturity around 14 months of age.

Why is my oscar fish laying on its side?

There are two main reasons why your oscar is lying on its side.

  1. Stress-if you just transferred your oscar fish to a new tank or changed other settings in your oscar fish aquarium your fish might be stressed or feel uncomfortable in its environment. You should first check your water parameters and then move on to address any new stressors in the tank.
  2. Submission-despite being a territorial fish if your oscar has just lost a fight or feels like it can’t win against other fish it will lay down in submission. Eventually it will return to swimming around, just make sure that there aren’t any bullies in the tank.

Temperament and Tankmates

Tiger Oscar Fish
Tiger Oscar Fish

When keeping oscars with companions you should carefully choose tank mates based on your experience.

Are oscar fish aggressive?

Yes! Oscars are one of the most aggressive fish you can have in a freshwater tank, and are even more threatening because of their size. You should avoid having any small fish, such as Rosy Red minnows, in Oscar tanks unless you intend for them to be live feeder fish.

Will an Oscar fish bite me?

Although they can bite humans, they rarely do. You might have heard us talk about how oscars have pharyngeal jaws, and thus have 2 sets of teeth (pharyngeal teeth in their throats and another set at the back of their mouths). Unlike piranhas or sharks their teeth are set fairly far back so as long as you keep your hand away from your oscars mouth you should have no trouble.

How many oscar fish should I keep?

The amount of oscar fish you keep is really dependent on your capacity to keep a large tank. One oscar fish requires at least a 75 gallon tank, each additional oscar should be allotted roughly 50 gallons. Keeping a tank with only oscars can get tough quickly based on size alone, but rest assured that oscar fish can be kept in solitary or with other fish.

What fish can live with oscar fish

As oscars are well known to be aggressive tank mates you will have to be especially careful when picking out companions to live in the same tank. Suitable tank mates should be peaceful and not tempted to provoke your oscar fish, but also large enough not to be mistaken as a snack. While you can keep multiple oscar fish together most aquarists don’t have the room for a large aquarium.

Compatible oscar fish tank mates

  1. Convict cichlid– another member of the cichlid family the convict cichlid’s black and white pattern will stand out against your bright oscars. They are similar in water condition needs to the oscar, and grow up to 6 inches meaning they’re unlikely to be mistaken for food.
  2. Jack Dempsey – another well known, very aggressive fish you should only keep a Jack Dempsey with an oscar if you are an experienced aquarist. The Jack Dempsey can reach sizes of 15 inches and need a tank size of at least 80 gallons.
  3. Green Terror Cichlid – These are one of our favorite hardy fish because of their feisty personality and unique coloring. As omnivores they require little fish care, but can be aggressive if threatened or don’t have enough space.
  4. Firemouth Cichlid – Another brightly colored fish that make excellent tank mates for your oscar fish, the firemouth cichlid is generally not aggressive unless spawning and is great for a beginner fish tank.
  5. Blood Parrot Fish – An excellent choice for a community aquarium as blood parrot cichlids are generally non aggressive. They can grow up to 12 inches and have similar tank condition requirements.

Other tropical fish that could make suitable companions include

Be aware that any fish on this list can turn aggressive if they feel like they don’t have enough space. Do research prior to purchasing any tank mates and find appropriately sized tanks.

Tank mates to avoid

Tank Requirements

Big Empty Fish Tank on White Background

While they are hardy fish proper oscar fish care should be observed as these fish are very sensitive to poor water quality.

Oscar fish tank setup

What kind of substrate to use for an oscar tank?

Oscars enjoy digging through substrate and for that reason sand and small gravel is best. They are also known for spitting out substrate into the water column which can cause filters to break if any substrate gets caught in it. We recommend buying a pre-filter to help mitigate this issue.


Uneaten fish food can fall into holes in the substrate and be buried, this can cause ammonia pockets which will ruin tank conditions when exposed. To avoid, only use an inch or so of substrate and be sure to clean any leftover food out of the tank.

Do I need to use a filter with an oscar?

Absolutely, oscars are known for being one of the messiest members of an aquarium and proper oscar fish care includes having a filter to help manage the bioload.

Should I use a heater in my oscar tank?

As oscar fish are used to tropical waters (75-80°F), it is a good idea to keep an aquarium heater in your tank.

Do I need an aquarium light?

Oscar fish don’t require any specific lighting, so unless you want to spotlight your tank with some fancy bulbs don’t feel pressured to include any for their sake.

Oscars and other fish often are stressed by high amounts of light for long periods of time so be sure that you allow them at least 12-16 hours of darkness.

Oscar Plants and Decoration

Like all fish, oscars require some tank decoration in their aquarium to provide stimulation, and hiding places. Funnily enough, you might notice that your oscar is a bit of an interior designer as they tend to move objects around. Because of this you should avoid breakable decorations and live plants.

PVC pipes, rocks, and a few plants are sure to keep your oscar happy and provide plenty of enrichment opportunities.


Oscars are known for their destructive tendencies to rearrange their tank. They will often shift substrate, dig up plants, and adjust decorations. If you’re trying to keep live plants in your tank consider floating plants as oscar fish won’t be able to uproot them.

What size tank do I need for Oscar fish?

For a single oscar fish you should count on having at least a 75 gallon tank. The more adult oscars you have the larger the tank should be, with roughly 50 extra gallons per fish.

The tank size isn’t only because oscar’s large size but also because they create a massive bioload that can be suffocating in smaller tanks.

Tank Shape

The shape of an oscar fish’s tank doesn’t matter as much as long as they have ample room to move around. While they do mostly stick to the bottom and middle of the water column it is nice to have a taller tank so other tank mates can swim in areas where they are not present.

Water Parameters

Tank Size>75 gallon tank
Water TypeFreshwater
Water Temperature75-80
Water pH6.0-8/0
Water hardness12-15 dGH


Red Oscar at the Bottom of a Fish Tank
Red Oscar at the Bottom of a Fish Tank

In most oscar fish care guides you will find the basic diet of oscars, we further elaborate by explaining how and when to feed your fish.


Oscar fish eat almost anything, in fact finding a healthy diet is one of the easiest aspects of oscar fish care.

What Do Oscar Fish Eat in Nature?

In the wild oscars are considered omnivores and will eat anything that will fit in their mouths. From plants, to insect eggs, to worms, and smaller fish your oscar likely won’t be picky when it comes to food.

What to feed Oscar fish?

You should try to keep your oscar’s diet close to one they would experience in the wild, this means fresh food including brine shrimp, feeder fish, mealworms, or even insect eggs. The key is providing a varied diet to avoid vitamin and mineral deficiencies. You should also supplement their diet with commercial food such as cichlid pellets that are designed to have all the nutrition oscar fish need.

When feeding your oscar fish be aware that many live fish food have too much fat and should be given to them sparingly. Pellets that are specifically designed for oscars should make up 70-80% of their diet.

When to feed Oscar fish?

Your oscar fish will likely always seem hungry, however they are prone to overfeeding and you should err on the side of caution.

Feed your oscar fish small amounts 2 to 3 times a day. The key to a healthy fish is better fish food, not more of it.

How much to feed Oscar fish?

Feed your Oscars using the three minute rule. This is where you drop two to three pieces of (appropriately sized) food in the water and allow your oscars to eat. Once the food is all gone add more and repeat until the end of the three minutes.

This process should happen 2 to 3 times a day.

How to feed oscar fish

Oscar fish food is fairly easy to use, and a majority of oscars will eat their food if you just drop it in the tank. Some fish might be lazy or old and prefer to wait until the food sinks to the bottom. 

If you are feeding your oscar fish live food like earthworms and don’t want to drop it in the tank or hand feed them use a pair of blunted tip tweezers.


Oscars are very intelligent fish, recognize their owners, and can be taught to take food from your hand or target feed.


Basic oscar fish care includes knowing common diseases your oscar is prone to and how to treat them. Diseases such as hole in the head disease and dropsy are not well known and can be fatal if not treated.

Common tropical fish diseases of oscar fish?

  • Ich – the fish keeper’s nightmare, pretty much all freshwater fish are susceptible to ich. Also known as the white spot disease, it is brought on by poor water quality, and weakened or stressed fish.
  • Hole in the head disease – Often fatal, it is not fully understood what causes hole in the head disease but it’s thought that it’s based on poor nutrition and/or bacteria. Hole in the head disease is particularly scary for new fisk owners because you’ll see cavities forming all over your fish’s head.
  • Fin/tail rot – A little less scary than hole in the head disease but just as serious fin/tail rot can be caused by an open wound becoming infected and lead to tattered fins, and in severe cases fins falling off.
  • Dropsy – Another disease that is almost as dangerous as hole in the head, dropsy is generally a sign of a more serious issue. Severe cases of bloating or constipation (oscar fish are prone to both) can lead to dropsy.

Oscar fish lifespan

On average oscar fish live for 10-13 years, though they have been known to live for nearly two decades. A majority of oscar fish growth takes place in the first year,sexual maturity is usually reached around 14 months, but some refuse to mate until year two or three.


Oscar fish in Aquarium, Astronotus ocellatus. aquarium with green plants, snag and stones. isolated fish close up
A Group of Young Oscar Fish Swimming Through Aquatic Plants

Oscars are monogamous, once you have an established breeding pair the process is easy.

Can you breed an Oscar fish?

Oscar fish breeding in captivity is possible but requires pristine water conditions. Additionally, you must have a tank that is large enough to house 6 oscars so that they can properly pair off.

Breeding oscar fish can start as early as 14 months of age and they can actively reproduce 3 to 4 times a year for the next 9-10 years.

How do Oscar fish reproduce?

To breed oscar fish you need both a male and female oscar fish. When the pair is ready to spawn they will begin a mating dance and move side to side, flaring their gills and fins. To replicate breeding season temperatures raise your water temperature above 77 degrees Fahrenheit (a few degrees is enough).

What do Oscar fish eggs look like?

Oscar fish eggs are opaque white, for first time breeders this is surprising as with other fish white eggs mean they are dead. The fish eggs are roughly a millimeter with, and are laid in evenly spaced rows.

How to breed an Oscar fish? 

Breeding oscar fish is fairly easy as they are excellent parents and will do most of the egg raising on their own.

Once the mating dance has been completed, your oscars will begin cleaning a flat surface to spawn on which generally takes 2-3 days. After this the female will swim over the nest site laying eggs in neat rows while the male follows behind her fertilizing them.

The parents will then defend the eggs and juvenile oscars.


First time parents or stressed oscars are prone to eating their young.

Here’s an example of successful oscar fish breeding.

Oscar Fish Breeding

Is the Oscar fish for you? 

If you’re looking for an interior designer that knows what they like, and has the bright coloring to match their bold personality the oscar fish is definitely for you.


In conclusion, in our oscar fish care guide we’ve reviewed proper care aspects, specific varieties of oscars, and what makes them unique for your tank. We hope that you fall in love with these fish as much as we have!