Amy Tokic
by Amy Tokic
fast facts

About Oscars

Aquarium Size
Very large (100+ gal)
Swimming Region
Fish Water Condition
Difficulty Of Care
Weekly care
Top Breed
Suitable Tank Mates
Large species of Catfish, Pacu, large species of South American Cichlids
General description

Oscar fish are one of the most popular species of freshwater fish in the aquarium hobby today. They are a highly intelligent species of fish and often display highly individual personalities, making them a favorite among many aquarists. They are characterized by their thick, rectangular shaped bodies and comparatively large heads. Oscars are a large species of fish and can easily reach 18 inches in length. They are also highly territorial as adults and should ideally be raised by more experienced aquarists.

Oscar fish are one of the most popular species of freshwater fish in the aquarium hobby today.


Oscars originate in the Amazon River basin in South America.


The primary colorations that Oscars occur in are black, brown, orange and red. Albino varieties have also been bred selectively over the years.

Maintenance and care

Although Oscars are often sold as young specimens of 2 inches or less, they can quickly outgrow most medium sized aquariums. They are also active swimmers and require aquariums with large open swimming space. Therefore it is important to house them in fairly large aquariums of 100 gallons or more. Oscars are also a very destructive species of fish and will uproot and destroy any plant life in the aquarium in a matter of hours. They are also fond of rearranging rocks and other aquarium decorations. This should be taken into account when decorating the aquarium.

Although the level of aggression can differ from individual to individual, Oscars are generally regarded as an aggressive and highly territorial species. They will often cordon off a specific area of the tank as their own territory and vehemently guard it against other fish regardless of species. Oscars are also aggressive fighters and will sometimes lock jaws and engage in long, drawn out wrestling matches to establish dominance. They are also highly predatory and will readily attack and devour smaller species of fish that they can fit in their mouths. They sometimes also attack larger, less aggressive species of fish like angelfish. For this reason they are best housed with large, moderately aggressive South American cichlids, large species of catfish or pacu.

Oscars produce a significant amount of waste and require aquariums with very strong filtration systems to prevent diseases caused by poor water quality.

Although Oscars are often sold as young specimens of 2 inches or less, they can quickly outgrow most medium sized aquariums.


Oscars are carnivores and can be fed on a diet of fish, worms, shellfish, shrimp and occasional servings of beef heart. They will also accept most meat-based pellet foods.


Oscars generally do not display obvious signs of sexual dimorphism and are often very difficult to sex. The best way to obtain a breeding pair is to raise 6 or more juveniles in a large aquarium and to let a pair form naturally. Once a breeding pair is formed, they will try to guard an extremely large territory in the aquarium and can sometimes even kill off most of their tank mates. Oscars should be provided with large, flat surfaces to lay their eggs on. Once the eggs are laid, both parents guard the spawn zealously. They also provide parental care for the fry after they are free swimming.

Aquarium varieties

Zebra Oscar, Tiger Oscar, Red Oscar, Albino Oscar, Veiltail Oscar, etc.

Photo credit: Ashish Ghosh/Wikimedia

Amy Tokic
Amy Tokic

Amy Tokic, Editor of PetGuide.com, is a passionate animal lover and proud pet parent of Oscar, a Shih Tzu/Chihuahua cross, and Zed, a Japanese Chin. Her love of animals began in kindergarten, when she brought her stuffed dog Snoopy into class with her every day. Now, she writes about her adventures in pet ownership and tirelessly researches products, news and health related issues she can share with other animal enthusiasts. In her free time, Amy loves perusing used book and record stores, obsessing over the latest pet products available and chasing squirrels with wild abandon (a habit attributed to spending too much time with her pooches).

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