Oscar Fish: What To Know About This Stunning Cichlid

Just about everybody knows the Oscar Fish.

They are by far the most popular South American Cichlid in the fishkeeping hobby.

Their popularity comes from their intelligence and appearance. You can find an Oscar in almost any color and it is sure to draw immediate attention to your aquarium.

Unfortunately, they are also notorious for being aggressive and temperamental.

This has caused them to have a mixed reputation in aquarium circles – people either love or hate them!

Are you thinking about getting your first Oscar?

Then keep reading to learn everything you need to know about this beautiful fish…

Group Of Oscar Fish

Oscar Fish Overview

Close Up Albino Oscar

The Oscar Fish (Astronotus ocellatus) is a large South American Cichlid that is native to the Amazon and Orinoco Rivers.

They are also known as the Marble or Velvet Cichlid and belong to the Cichlidae family.

This fish is one of the most popular freshwater fish around and they are well known for their vibrant colors and fierce aggression. You will most commonly find them in the Tiger or Black scale pattern, but there are many other color forms available.

A basic Tiger Oscar costs about $20 with specialty colors costing at least $30 and ranging up to $200.

However Oscar Fish are not the right fish to buy for a first time fish keeper. Not only do they live for up to 20 years but they need large aquariums as they can grow up to 15 inches long.

Key Facts:

  • Experience Required: Cichlid Keeping.
  • Nicknames: Marble Cichlid, Velvet Cichlid.
  • Color Forms: Tiger, black, red, orange, yellow, blue and green.
  • Size: 12-15 inches.
  • Tank Size: Minimum 75+ gallon.
  • Tank Temperature: 75°F-82°F.

Pros and Cons


  • Colorful and eye-catching.
  • Are compatible with other large fish.
  • Very intelligent and can be trained.
  • Lots of different types available.

  • Need a large aquarium.
  • Preys on other fish and invertebrates.
  • Digs up and damages plants.
  • Can sometimes bite their keeper.

Oscar Fish Appearance

Blue Astronotus ocellatus

Oscars are similar in size and appearance to Pumpkinseed Sunfish and others in the Centrarchidae family.

They have bulky and oval shaped bodies with bull heads and sloping foreheads.

In total they have 7 different fins although some aquarists count their fused dorsal fin as 2 separate fins. The other fins include the anal, caudal, and paired pectoral and pelvic fins.

Towards their forehead their dorsal fin has several small spines that prick upward if they are startled or handled incorrectly. Also if you take a look at the caudal fin, you will notice a small orange or yellow spot. This is called an eye spot and it is meant to confuse predators.

Their thick and stocky body shape makes it difficult for these fish to swim very fast or keep up with high currents. They usually swim with their mouths open in order to regulate oxygen intake. Most Oscar Fish will grow to around 12 inches long.

This species is not sexually dimorphic so you will have to rely on your aquarium supplier to tell you if your fish is male or female.

Their colors and patterns will vary depending on the type of setup that they are raised in – this is a survival tactic which helps them blend in with their environment.

Expect their scales to have a glossy appearance which shows up particularly well on a jet black fish.

Types of Oscar Fish

The typical color form is a very vivid black and orange.

However, many other colors are available too including blue and yellow.

Red, orange, or yellow appears as a banded or lattice pattern against black, grey, or dark brown scales. The lattice is usually present towards the caudal end of the fish.

On light color forms such as Lemon or Albino, the bands or lattice occur against a white or light pink background.

This fish comes in many beautiful color forms, here are all of the different color forms that you can find:

Tiger Oscar Fish: This is the typical color form and the one most widely available at pet shops and aquarium suppliers. They are known as Halloween fish because of their orange and black coloration. The base color can be jet black, dark grey, dark brown, or a mix of all three. Orange or red appears in bands or lattices towards their caudal fin. Some Tigers have an orange and black swirl or mosaic pattern.

Red Oscar Fish: A Red Oscar has an orange or red body and fins with black or grey heads. On this variety black and grey occurs on the forehead and as a border along the fins. The light and dark colors join towards the caudal fin.

Albino Oscar Fish: Albino Oscars have solid white or light pink bodies, with deep red or orange bands or lattices. Their eyes may be yellow, pink, or light red.

Lemon Oscar Fish: This cream colored variety is not the result of albinism or leucism. Lemon is another color that is specially bred in aquariums. Lemon is a particularly popular color form and they have a yellow lattice pattern over a cream colored base.

Black Oscar Fish: Unlike many of the other color forms the black color form can occur naturally. To be considered black the fish simply must have more black scales than orange or red. Orange and red may appear as spots rather than bands or a full lattice. In rare cases the fish can be solid black, but they are usually a mixture of black, grey, and brown.

Blue Oscar Fish: They are the result of crossbreeding and will look similar to an Electric Blue Ram or Blue Acara. A solid blue fish with no orange color is especially prized. If orange colors do appear they occur in a banded or lattice pattern as with the Tiger variety.

Green Oscar Fish: This is the rarest color of all and is extremely prized by breeders. Like the blue variety they are the result of crossbreeding. The green color can manifest in two different ways: as part of the banded or lattice pattern, or as the base color. The former is much rarer and more sought after.

Habitat and Tank Conditions

Astronotus ocellatus

These fish are native to South America and can be found basking in dark substrate and under rocks and logs. They will shelter in anything that they can blend in with.

Oscars tend to stay in slower moving areas of the river where they can lie in wait for prey to ambush.

Murky and turbid environments help them to hide effectively.

Let’s look at how to create these conditions in your home aquarium.

Ideal Tank Set Up

The first thing you will need is at least a 75 gallon aquarium.

You can keep them in a tank or in a heated outdoor pond – either way the temperature must be kept between 75-82°F.

The tank’s pH can range between 6.0-7.5 and a hardness between 5-18 dGH.

Light intensity does not matter as they prefer the darker areas of your setup. You can use any kind of aquarium light that you prefer.

You will need a hood to stop mischievous Oscar Fish from squirting or splashing water.

Because these fish generate a lot of waste you will need a more powerful filter than usual. You should use an external or canister filter that can run several different currents at a time. Just remember to keep the current near the bottom levels of the tank slow.

Now onto the substrate.

This should be either dark soft gravel or dark smooth rocks. These fish love to dig so avoid using rough substrate.

You can also decorate the bottom with rocks, logs, and other good hiding places. Your Oscar will pick out a particular spot to establish their territory.

As for other decorations you will also need to consider plants.

Oscar Fish are notorious for digging them up, so it is best to use floating plants to provide a little extra cover. Hornwort, Duckweed, Anacharis, and Frogbit are all excellent floating plants that you can use.

Tank Parameter Requirement
Minimum Tank Size 75 Gallons
Tank Type Freshwater
Temperature 75-82°F
pH 6.0-7.5
Hardness 5-18 dGH
Flow Light
Substrate Dark and soft substrate

What Size Aquarium Do They Need?

The minimum tank size for just one Oscar is 75 gallons.

You should add an extra 50 gallons for each additional Oscar Fish.

Tank Mates

Oscar Tank Mates

In the wild these fish cohabitate with many other species.

However when kept in an aquarium it is very risky to keep them with other species. They will eat anything that is small enough to fit in their big mouths and they tend to harass and bully anything that they cannot eat.

The easiest way to keep them is in a single species only tank.

However if you really want to keep them in a community tank it is possible – you just need to be very careful and pick the right tank mates.

You can include other large and aggressive South American Cichlids such as: Jack Dempseys, Convicts, Green Terrors, and Firemouths.

If you have a pond or a super-sized tank then you can keep them with: Bichirs, Bala Sharks, or Arowanas.

Sailfin and Common Plecos are both large enough to be left alone and peaceful enough not to cause any trouble. They have the added bonus of being algae cleaners too. You can also consider Silver Dollars too.

You should avoid any invertebrates and also any fish that are smaller that 6 inches.

Peaceful Cichlids like Blood Parrots and Discus will not be able to defend themselves against this fish’s bullying behavior, so they should be left out of this particular community.

Finally, you should avoid mixing South American and African Cichlids together – African Cichlids can carry diseases and parasites that will kill South American Cichlids.

Keeping Oscar Fish Together

Keeping these fish with their own kind is much safer than trying to create a community.

Each Oscar in your tank will establish their own territory and they will fiercely defend it. Because of this your aquarium must have enough space to accommodate them all.

You will need at least a 125 gallon aquarium for more than one Oscar Fish.

However if you are new to the species then we recommend you start out with a single species tank.

Oscar Fish Care

Pair of Blue Oscar Fish

Anyone looking to take on this species should have experience with other aggressive Cichlids.

These fish are not well suited for first time keepers because their setup needs a lot of equipment which can be expensive and demanding to maintain.

They are also susceptible to many common fish diseases, including ich and fin rot.

Hole in the head disease is one of the most common and serious illnesses that they can develop. This disease is the result of a bacterial infection or a Hexamita parasite. It often occurs in dirty or poorly filtered tanks and small dents or lesions develop on the fish’s forehead or between their eyes.

Treating the illness is difficult, as you will first have to determine its cause. Antibiotics can cure a bacterial infection, but you will need to take other measures if it is the result of a Hexamita infection.

Just remember that an ounce of prevention is worth a pound of cure. Keeping the tank clean and the filters maintained is the best way to prevent any harmful parasites and bacteria from infecting your fish.


In the wild this fish will eat small fish, worms, snails, bugs, and even small frogs.

Live prey makes up most of their diet.

While hunting for prey they hide and wait under the cover of rocks or dark substrate. When a critter scurries by they will lunge at it and gobble it up.

You should try to encourage their natural hunting instinct too.

Do not expect to toss in a few fish flakes and call it a day.

Give your Oscar Fish food that they can ambush, such as feeder fish and small shrimp. Minnows and Fundulus fish, Grass Shrimp, and Ghost Shrimp are all great choices. You can also give them aquatic and terrestrial insects (like crickets and water beetles). Bloodworms and crayfish are also great protein-packed snacks.

You should also give them algae flakes or Spirulina tabs so they can get their greens too.

If you are into homemade fish food, you can offer some peas, cucumbers, bananas, and leafy vegetables as an occasional treat.

This fish is not a finicky eater. Here are all of the different foods they will eat:

  • Feeder fish
  • Ghost Shrimp
  • Grass Shrimp
  • Amano Shrimp
  • Crayfish
  • Insects and insect larvae
  • Bloodworms
  • Snails
  • Cichlid flakes
  • Algae flakes and pellets (supplement)
  • Spirulina (supplement)
  • Cucumbers
  • Peas
  • Lettuce
  • Spinach
  • Bananas

These voracious eaters are notorious for stealing food from each other and their tank mates. You will have to feed them up to 3 times a day to keep them satisfied enough to stop this.

If you place the food close by your Oscar’s chosen territory then it can help limit the amount of fights and food theft in your aquarium.

Albino Oscar Fish


Unfortunately this fish is very aggressive and can be hard to keep with tank mates.

They usually live at the bottom of the tank and stay close by their chosen home, but will venture out into the middle of the water column to hunt.

You might find them moving rocks and boulders around or digging up any plants in their area. This might mean that they are planning to establish a new territory or cleaning out the area for a nest.

A common behavior is you might spot is them kissing. Kissing Cichlids are not kissing, they are fighting. This is their way of defending their territory and establishing dominance over other fish (especially when competing for a female).

Oscars can also learn to recognize their keeper and will come to you for food and attention. But they also have a bit of a mischievous side.

When they are feeling playful they may squirt or splash water at you.

They may also chase after your fingers during feeding or cleaning.

Breeding Oscar Fish

One of the hardest parts of breeding Oscars is correctly sexing the males and females (read our appearance section for more guidance).

Once they do pair off breeding comes quick and easy.

You should keep a breeding pair in a separate tank where they cannot attack other fish. If they are kept in a community tank they will attack anything that gets in their way, including your fingers! Do not handle or disturb fish that are nesting or getting ready to spawn.

Once the female selects her mate, they will immediately start to build their nest. Any decorations in the nesting area will be moved or turned over. They will then mate and a female can lay up to 2000 eggs during this time. But not all of these eggs will hatch or survive to adulthood.

Both parents will care for the eggs and fry.

You should crush up Cichlid flakes into powder for the little ones to eat.

Once the fry are free-swimming and hunting for their own prey, you can move the parents back into the main tank. The fry can be given brine shrimp, insect larvae, and other tiny prey to hunt.

It takes 2 years for young Oscar Fish to reach full maturity, but you can place them in the main tank once they reach around 6 inches long.

Oscar Fish

History and First Sighting

The Oscar fish was first discovered by Agassiz in 1831.

They were initially given the name Lobotes ocellatus, however Lobotes is a genus that is reserved for saltwater fish.

It was mistakenly believed that the species was native to the Atlantic Ocean. Once this mistake was corrected, their genus was changed from Lobotes to Astronotus.

During the 1940s and 50s fishing ponds in the southern United States were stocked with imported Oscar Fish. Recreational fishermen prized them as trophies.

However it was not until the 1980s when this species graduated from a game fish to an aquarium fish.

Throughout the 2000s and 2010s their popularity continued to soar and now they are one of the most popular freshwater fish around.

FAQs About Oscar Fish

What do Oscar fish eat?

These fish are not very fussy about their food and they will eat just about anything they can fit into their mouths. Shrimp, crabs, crayfish, and small fish are among their favorite foods. In outdoor ponds, they will even eat small frogs and salamanders.

How big do Oscar Fish get?

A fully grown Oscar Fish can reach up to 15 inches in just under 2 years. On average, they remain at about 12-13 inches long.

How long do Oscar fish live?

Oscars can live anywhere from 10-20 years.

The Oscar’s lifespan is one of the most important things to remember when deciding to keep one.

How much does an Oscar fish cost?

Most Oscars will cost between $20-$25, wit more specialty colors selling for over $200. The most expensive color form is Green, which sells at over $200 at some dealers.

Species Summary Table

Oscar Fish
Other Common Names: Marble Cichlid, Velvet Cichlid
Scientific Name: Astronotus ocellatus
Family Name: Cichlidae
Distribution: Peru to Paraguay
Size: 12-15 inches
Color: Black and orange, red, orange, green, blue, yellow, black, albino
Care Level: Advanced
Temperament: Aggressive
Lifespan: 10-20 years
Minimum Tank Size: 75 gallons
Tank Mate Compatibility: Single species or other large fish

Should You Keep The Oscar Fish? (Summary)

Just remember that the Oscar Fish is a major commitment and not everybody is able to handle them.

These fish are not an impulse buy because they grow very large, live a long time, and need a lot of care.

However for those people that can provide a suitable home for Oscars, this is certainly a special fish. You will be charmed by their intelligence and personality. They are truly fascinating to watch one action. With all of their quirks, tricks, and games, it is difficult not to fall in love with them.

With several colors to choose from and plenty to admire about each one, an Oscar Fish might be the perfect addition to your tank.

How does your Oscar like to keep busy?

Let us know in the comments section below…