Do you own an Oscar Fish Tank or Looking to start an Oscar Fish Tank?

Taking care of Oscar can be quite a challenge if, few important points are not taken care of

In this Guide we will explain everything you need to know about Oscar Fish Care, what to feed them, how to breed etc..

Recommended Equipment for Beginner Oscar Tank Setup

Here is a quick list of recommended equipment for beginners looking to start an Oscar Fish Tank

SeaClear 50 gal Acrylic Aquarium Combo Set, 36 by 15 by 20', Clear
SeaClear 50 gal Acrylic Aquarium Combo Set, 36 by 15 by 20", Clear
Combo includes aquarium, reflector and electrical 24" light fixture; Acrylic aquariums are clearer than glass, 17 times stronger, and only half the weight!
JBJ True Temp Titanium Heating System Kit for Aquariums, 500-watt
JBJ True Temp Titanium Heating System Kit for Aquariums, 500-watt
Remote temperature probe; Large constant LED display of the current temperature; Country Of Origin: China
NICREW ClassicLED Aquarium Light, Fish Tank Light with Extendable Brackets, White and Blue LEDs, Size 18 to 24 Inch, 11 Watts
NICREW ClassicLED Aquarium Light, Fish Tank Light with Extendable Brackets, White and Blue LEDs, Size 18 to 24 Inch, 11 Watts
Allow to easy install on a variety of aquarium with extendable mounting brackets
Polar Aurora Free Media 4-Stage External Canister Filter with 9-watt Light, 525 GPH with Free Media
Polar Aurora Free Media 4-Stage External Canister Filter with 9-watt Light, 525 GPH with Free Media
Good for up to 200 gallon fish tanks. Maximum flow rate of 525GPH from built in pump; Built in 9 Watt Light for promoting clear water. With free media.
Tetra Whisper Easy to Use Air Pump for Aquariums (Non-UL)
Tetra Whisper Easy to Use Air Pump for Aquariums (Non-UL)
POWERFUL Tetra Whisper Air Pump provides dependable airflow to your aquarium; QUIET Patented dome shape suspended motor and sound-dampening chambers for quiet operation
Tetra SafeStart Plus 250 mL, for Newly Set-Up Fish Aquariums
Tetra SafeStart Plus 250 mL, for Newly Set-Up Fish Aquariums
REDUCES TOXINS: Helps remove dangerous levels of ammonia and nitrite.; included components: 1 x SafeStart Plus

Last update on 2022-04-15 / Affiliate links / Images from Amazon Product Advertising API

Caring for Oscar Fish

1. Oscar Fish Need Big Tanks

The minimum tank size should be a tank that can hold at least 152 litres or 50 gallons of water see our Aquarium Tank Guide.

2. Big Filters are needed for Oscar Tanks

It is necessary to have excessive filtration of the recycled water in the whole aquarium since they are messy species and requires regular maintenance of its environment.

Also, since Oscar are big fish they need bigger tanks which increases the need for a bigger filter.

The overstayed water become Toxic water  and affects health of fish badly. A filter system at the inlet or water cycle are the best solution to keep them healthy.

Read our reviews of Best Aquarium Filters for choosing the best suited filter for your oscar tank.

3. Maintain Aquarium Temperature

The temperature of water tank should be maintained between 23 to 27 degrees Celcius or 77 degrees Fafrenheit. A aquarium heater with temperature controller will ensure the stability in temperature inside the tank.

4. Do Regular Water Changes

Every week around 10-15% of the water in the tank need to be changed with fresh water to maintain the water quality in the tank.

5. Test the Water Quality Regularly

Use a good quality water test kit which checks for multiple parameters once a week. This makes sure the water remain within various parameters and is not becoming toxic for the fish. Read our detailed guide on Water Testing and what you need to look at.

Also read our reviews of Best Water Test Kits available.

6. Feed Oscars Regularly but Avoid Overfeeding

Oscars are not a very picky eaters, but they require regular feeding for proper growth. All details related to oscar feeding in given in next section.

Oscar Food & Feeding Guide

What do Oscar fish eat

Oscar can eat almost everything that falls into the water tank. Oscars mainly eat freshwater insects and crustaceans. They do not eat fish which means that they are not piscivores.

Even if they do eat fish, it contributes to a minor portion of what they eat and primary fish food of Oscars are catfish in their natural environment. 

So, you should remember this while choosing tank mates for your fish and should never put catfish in the water tank as mates for your Oscar fish.

What Should I Feed Oscar Fish

A proper diet increases their life expectancy and strengthens their immune system. They should be fed with prepared fish food such as crayfish, insects and worms.

Food Rich in Vitamin C

In diet, the Oscars have high requirement of Vitamin C. So, they like to eat fresh fruits to meet their vitamin C requirement. Different fresh fruits and vegetables can be provided to Oscar as supplement food.

Algae & Plants

Oscar’s diet also contains algae and plants and they never seek for algae or green plants and feed them only because these are the main contents of their prime prey.

Dried Foods

Oscar’s diet mainly consists of dried foods which is a problem for fish as they contribute to blockage, bloat and constipation resulting in the death of fish.

Dry foods containing probiotics are a solution to this problem as they minimize risks of constipation, blockage and bloat in fish, but still supplement foods with high level moisture content should be chosen as the best option.  

High Quality Cichlid Pellets

They should be given quality pellet with good quality plant and algae in their diet containing significant amount of nutrition, proteins and vitamins necessary for your fish. Flakes are not acceptable for Oscars.

It should never be the primary food for your fish as they are inferior than pellet food when it comes to nutrition. Also, they are large and Oscars finds it very difficult to eat. So, while you are feeding your fish, you should feed them with best quality pellet.

Oscar Feeding Guide

Feed Oscars Once a Day

Its best to feed oscars every 24 hours with quantity it can eat in 2-3 minutes. However, you need to be regular in feeding it around the same time everyday to avoid it going hungry.

Avoid Overfeeding

Also, they will eat all that you give it, so avoid overfeeding it as it may lead to various problems including constipation

Should I feed Live Foods

Feeding live foods increases growth rate,the but also causes disease like endoparasites. Do not feed your fish mammalian flesh as they cause fatty liver disease.

Also, Avoid feeding it with small live fish like the goldfish. Instead, feed them with insects or processed food.

How to cure Oscar Constipation

Green peas are used to cure Oscars having constipation whereas if you are giving fruits and vegetables to your fish, you should ensure that all seeds are removed from them prior to feeding to eliminate risk of blockage.

Remove any Uneaten Foods

These foods also deteriorate water. So, you should also ensure that your fish eats them away as soon as they are fed or are removed from the water tank. As they primarily feed on dry foods.

Give Good Quality Cichlid Pellets

Therefore, they should be given quality pellet with good quality plant and algae in their diet containing significant amount of nutrition, proteins and vitamins necessary for your fish.

Flakes are not acceptable for Oscars.

It should never be the primary food for your fish as they are inferior than pellet food when it comes to nutrition. Also, they are large and Oscars finds it very difficult to eat. So, while you are feeding your fish, you should feed them with best quality pellet.

Oscar Breeding Tips

Do Oscars lay eggs

Oscar lays eggs, but most of them eats away first egg and second too. Female gives birth to eggs after 2 to 3 days of the mating process in batches of 100 eggs and in total, lays 1000 eggs within a period of a few days.

In the natural habitat, Oscar eggs often have a low success rate and only a few eggs mature into young adults but  if cultivated in captivity like  tank or aquarium , they have high conversion rates.

This point can be taken as a base while selecting rearing water tanks for your fish. After eggs are laid, within 72 hours Oscar fry hatch. If Oscar pair becomes upset, is in stress or feeling unsafe,

they  consume their eggs. Fertilized Oscar eggs will be light brown in color as compared to white colored unfertilized eggs. As Oscar fry are hatched, you should move them to a different tank to eliminate the risk of being consumed by parents.

Moving them to different rearing tank will raise their survival rate and they will start to grow and will require more and more space as they grow into a large Oscar fish. Female Oscar lay a large number of eggs ranging from 1000 to 2000 eggs on clean rocks.

Sexing Oscars

It is impossible to tell the difference in sex in case of the Oscars. Both male and female types look alike and show no difference in length or size but you can differentiate them by looking at the shape of genital papillae located somewhat around their anal opening which is blunt and wide-mouthed in females.


Mating starts with a pair of fish involved in activities like nipping, chasing each other, picking up sand in mouths and relocating it somewhere else in the tank. Once they decide to mate, they prepare an area to lay their eggs on.

Oscars male and female pairs that are chosen for mating process should be minimum two years of age. It is an easy way to mate if you buy a pair of Oscar’s that are spawned and mated already at least once.

These already spawned fishes spawn naturally each month. When you buy, do not forget to ask for spawning proof. In case you do not buy this pair, next option you can choose is to buy some juveniles,

grow them into adults and wait till they pick up their partners naturally for mating. Choosing this option will cost you enough time in breeding process which can be 16 months and varies from fish to fish.

Breeding signs

Pair of Oscars seen cleaning a flat surface expresses early breeding behavior. At the time of breeding, courtship behavior can also be violent.

How to get Oscars to breed

Purchase a pair  that have already been bred in past and pair them off in your aquarium for successful breeding. Interbreeding different types of Oscars like Albino, Tigers, Reds, Whites, Yellows allows you to have more Oscars with most distinct and unusual colors.

You are able to interbreed Oscar types to come out with the most unusual colors. Large space should be provided to Oscar pairs while breeding, a breeding tank of 100 gallons is preferred. Breeding them is like a challenge which can be met if you are dedicated towards it.

Mating habits

Oscar pair shows mating habits such as change in swimming habits, slapping tails, chasing and lip lock mouths. In worst cases, they sometimes attack each other.

Oscars should be given varied diet, tank water should be changed twice a week to keep it clean to induce spawning behavior. When spawning behavior is seen in Oscars, there comes a need to provide the pair with a spawning medium which can be an upturned dinner plate.  Ceramic surface is also suitable to lay eggs.

Other Oscar Information

Oscar fish belongs to cichlid family and are known by scientific name Astronotus ocellatus.

They thrive best in their natural habitat which is located throughout Amazon River basin in South America. When you plan to cultivate them, you should be aware of all facts and information in advance.

What is an Oscar Fish

They belong to cichlid family  and is well known by many common names like tiger Oscar, marble cichlid and velvet cichlid.

It resides in its natural wild habitat in South America and has also been introduced to many parts of the world like China,  the United States and Australia. It is one of the famous aquarium fish in the U.S.


These species were originally discovered by Louis Agassiz as Lobotes ocellatus in 1831. It was a mistake as the species was marine and later on more work was done and finally the genus Astronotus name was assigned to the species.

This species has many numbers of synonyms such as Acara compressus, Astronotus ocellatus zebra, Acara hyposticta,  and Astronotus orbiculatus.

Life span of Oscars

The life span of Oscar fish are generally 10 – 13 years.

Difference between male and female Oscar fish

Color differences can’t differentiate males from female. It is the shape of genital papillae that clearly differentiates male from female.

When Oscars are large enough to be between 4 and 5 inches in length, you can examine them by observing genital papillae. In case of males, this forms into a fine point and is blunt and wide-mouthed in case of females.

Oscar Fish Colors

In the wild natural habitat, Oscars have dark-colored bodies with yellow colored ringed spots known as ocelli and are located on caudal peduncle and dorsal fin.

They can change their colors, this unique feature protects them being from being eaten while they feed in their territory. Juveniles of this species show many different colors as compared to adults like  they have strips of orange and white bands.

Do Oscar have teeth

Oscars do have teeth that are placed at back in the mouths. Their teeth are not as sharp as a razor but are shocking enough to get chomped by. They have teeth not only in jaws, but they also do have set of pharyngeal teeth in the throat as well.

Oscar jaw teeth are very small and are only used for grasping whereas teeth in the throat processes and manipulates prey. 

If you consider type and arrangement of teeth then pharyngeal teeth in the throat are arranged in such a way that they are considered as one of important character of Oscar fish helpful in systematic process in deciphering evolution of cichlids and significant study has already been published.

How Big do Oscar Grow

  • Biggest Oscar fish: Approximately 18 inches in size, Oscar is the world’s biggest fish ever recorded.
  • Oscar growth rate: An Oscar grows between 8 to 10 inches in a year, growing pretty fast if you get them a large tank to provide enough space.
  • Giant/Huge Oscar fish: A giant Oscar fish is generally between 17 to 18 inches in size.
  • Largest Oscar fish are found to be between 20 to 22 inches in size.
  • Full grown Oscar fish: Oscars grow up to 18 inches in length and weigh approximately more than three pounds when at maturity. If kept in captivity, Oscar fish grows up to 12 inches in length but larger specimens of Oscars have already been reported.
  • Measuring Oscars: Measure your Oscar fish with the help of string or a ruler, putting it up to the glass of water tank and don’t take fish out of the tank to measure.
  • Dwarf Oscars are stunted Oscars, but they are extremely rare
  • Short Bodied Oscar: Oscar fish are selectively bred to have shorter, compact body and are known as short bodied Oscars.

Suitable Oscar Fish Tank Mates

Although Oscars can live on their own all alone and do not have any need of tank mates but some of the compatible partners are Black ConvictsFiremouthJack DempseyChocolate CichildsKnow More

Oscar Fish Diseases, Prevention & Cure

They are affected by five general diseases which are hole in the head, ich, popeye disease, fin and tail rot,  and bloat. Common diseases are IckFin & Tail RotDropsy.

Overcrowding and bad water quality causes these diseases. These are most vulnerable to head and lateral line erosion also known as hole in the head disease.

This disease mainly affects the head and face, and when you see, they look like cavities and pits over head and face. It is caused due to nutritional deficiency of: Vitamin D, Vitamin C, and elements like calcium or phosphorus,

which is due to intake of insufficient and poor diet that lacks in variety and is also a result of partial water changes or over-chemical filtration with activated oxygen as chemical medium.

You need to monitor them periodically and diligently for injuries or diseases at regular intervals of time. While cultivating this fish, you should have full information about a variety of infections like parasitic infections, fungal infections and bacterial infections.

You are also advised to have more knowledge about water tank diseases and knowing the symptoms, treatment of all types of diseases which help you in cultivating happy and healthy fish. Take precautions as prevention is better than cure.

How Oscars Behave

Oscars capture and claim areas of aquarium and will show aggression if other fish encroach their established territory. They like to live alone in their defined territory and do not like to live in community.

Generally, they are not aggressive and belligerent by behavior and never show aggression towards other tank mates but they are considered as predators who will eat their tank mates.

Still, it is not difficult to grow Oscars with other tank mates provided they have large fish as their tank mates in a large spaced aquarium of about 200 gallons.

Oscars know their owner very well and are one of the amicable fish swimming around in water tank getting bonded with their owners. 

For example, they love to watch day to day happenings in and around the room and also react to the sounds of their owner known for their begging for food and for performing rolling ticks.

Oscars also love playing with toys and while playing, they love to dig up plants, place tank decorative things from one place to another. 

They have aggressive temperament and they are a threat to peaceful fish who are slow swimmers and slow eaters. They also prove to be threat for shrimps, snails and crabs.

Oscar Fish Names

Selecting a name for your fish is one of the important part of fish care. It helps you to distinguish your fish so you can easily take care of your special or loved one fish. You can refer a complete list of fish names.

Oscar Tank & Bowl

 It can be quite sad, waking up to find sick or otherwise dead fish in the aquarium. They need very special care and attention.   Look at our Tank Accessories Guide for more information.

Oscar Fish for Sale


Prices vary depending on different sizes and varieties. The  most common, popular and young are priced low and are cheap.

Also, the price depends on the growth rate of your fish as high growth rate will need a tank that have large space such that they can fit into it as they grow and mature into a large sized fish.

The cost is generally between 5 to 15 dollars for young, small Oscars with a large spaced tank will cost somewhat around 100 to 300 dollars. Also, it will be good if you do some research before you buy your fish as price varies and depends on various parameters.

Buy Oscar fish online

These breeds are available online in fish stores in varied varieties and coloration. There are many online websites available to shop and buy your favorite Oscars as per your desires and specifications on reasonable rates.

You can also get all supplements online needed to cultivate your fish and to ensure that your fish grows into a happy, healthy, mature fish with no stress and fear.


[Revised and Updated for July, 2019]
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Written by Debra Hutchinson, founder of FishXperts