Oscar Eat Fruit in the Wild

Astronotus ocellatus is a species of fish from the cichlid family known under a variety of common names, including oscar, tiger oscar, velvet cichlid, and marble cichlid. In South America, where the species naturally resides, A. ocellatus (oscar) specimens are often found for sale as a food fish in the local markets. The fish has been introduced to other areas, including China, Australia, and the United States. It is considered a popular aquarium fish in the U.S.

A. ocellatus (oscar) examples have been reported to grow to about 45 cm (18 in) in length and 1.6 kilograms (3.5 lb) in weight.  The wild-caught forms of the species are typically darkly coloured with yellow-ringed spots or ocelli on the caudal peduncle and on the dorsal fin. These ocelli have been suggested to function to limit fin-nipping by piranha (Serrasalmus spp.), which co-occur with A. ocellatus in its natural environment. The species is also able to rapidly alter its colouration, a trait which facilitates ritualised territorial and combat behaviours amongst conspecifics.  Juvenile oscars have a different colouration from adults, and are striped with white and orange wavy bands and have spotted heads.

In the aquarium hobby oscars may be fed prepared fish food designed for large carnivorous fish: crayfish, worms, and insects (such as flies, crickets and grasshoppers). Feeding live foods may increase the rate of growth but also may cause endoparasites. Poultry and/or mammalian flesh, including beefheart, should not be fed long term as these fatty foods will contribute to fatty liver disease. Since these fish eat fruit in the wild, items such as melons, oranges, and other fruits can also be used as a type of food. Just about anything that falls into the water would be eaten by oscars. Live feeder fish can be given, but fish such as goldfish and rosy red feeder minnows should not be fed. These contain an enzyme (thiaminase) within their flesh which binds vitamin B₁, leading to deficiency.