The Oscar (Astronotus ocellatus) is a species of fish from the cichlid family known under a variety of common names, including oscar, tiger oscar, velvet cichlid, or marble cichlid. In South America, where the species naturally resides, A. ocellatus specimens are often found for sale as a food fish in the local markets. The fish can also be found in other areas, including China, Australia, and the United States. It is considered a popular aquarium fish in the U.S.
The species was originally described by Louis Agassiz in 1831 as Lobotes ocellatus, as he mistakenly believed the species was marine; later work assigned the species to the genus Astronotus. The species also has a number of junior synonyms: Acara compressus, Acara hyposticta, Astronotus ocellatus zebra, and Astronotus orbiculatus.