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Scientific Name:  Astronotus ocellatus      
Min. Tank Size:   125 gallons      
Personality:   Aggressive      
Temperature:   75-82°F      
pH:   6.0-7.5/5-20°dGH      
Size:   12"      
Diet:   Omnivore      
Breeding:   Egglayer      


Can be kept with other large-growing species like Cichlids, Catfish, Cyprinids and Loaches, but will require a much larger tank than the minimum recommended.


Also known as the Peacock, Velvet and Marble Cichlid, Oscars are extremely popular in the aquarium hobby. Wild-caught specimens of these fish are typically dark in coloration with black, orange-ringed spots on the caudal and dorsal fins. Captive-bred and selectively bred specimens are also available in various colors, as well as tiger and albino strains. In the wild, Oscars are widely distributed throughout Venezuela, Colombia, Peru, Brazil and other parts of South America. These fish tend to inhabit slow-flowing waters in forested areas and seem to prefer white water habitats where there is plenty of submerged and marginal vegetation to provide cover.

Tank Set-up

Because this species grows very large, they require a sizeable tank. For a single specimen, a 125 gallon tank is recommended. The ideal Oscar tank would be decorated with sandy substrate and large driftwood branches. The lighting in an Oscar tank should be subdued and efficient, high quality filtration should be accompanied by weekly 25% to 50% water changes. A regular water maintenance routine is essential since these fish are very messy eaters and produce a lot of waste. Unfortunately, this important fact is often understated or not mentioned at all to the unwary buyer of the cute little 3" juveniles at the pet store. Oscars also have the reputation of totally decimating the interior of an aquarium. Therefore, you should ensure that tank decorations and equipment are firmly secured. Any stacked rocks should be secured with aquarium safe epoxy. Heaters and filter intake/return lines should be firmly secured as well. A popular technique for occupying the attention of the Oscar is to place ping-pong balls or other "toys" in the aquarium. As long as the tank is big enough, Oscars can be kept with other large species such as Cichlids, Catfish and Cyprinids.


In the wild, Oscars are omnivores, feeding on a variety of foods including other fish, insects and crustaceans as well as vegetation. In the home aquarium, Oscars should be fed meat-based foods along with fresh vegetables. Feed a varied diet consisting of earthworms, prawns, and a good quality Cichlid pellet. Although feeding live feeder fish like guppies and goldfish makes for an exciting show, it is not recommended since this is an excellent way to introduce diseases into the aquarium, and more importantly, into your Oscar!


Breeding Oscars is relatively easy once you have established a breeding pair - this can be quite difficult because this species is not easily sexed. The breeding tank should be fairly large and should be decorated with several flat rocks as spawning sites for these substrate-spawning fish. Raising the temperature in the breeding tank is a simple way to encourage spawning behavior and, once spawning occurs, more than 1000 fry per brood may be produced.

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