While you can generally purchase these fish while they are still very small, they will grow quickly and need a large tank. An Oscar fish can grow to be 12" or even larger and when they reach that size they would need at least a 55 Gal. tank. I recommend a 75 Gal. tank for a pair of full-grown Oscars. I have the Solana 67 Gallon Aquarium System and I recommend it as a good option for one or two Oscars.
Oscars are territorial and should not be kept with any fish that isn't big enough to defend it's self. They will eat anything they think is small enough to eat and may attack and injure a more timid tank mate. I would keep Oscars in a species tank, keeping only a pair of them in the tank with a cleaning fish like a Pleco.
Oscars will eat a wide variety of food including flakes, pellets and live foods. To keep them healthy and their colors bright, it is recommended that a regular diet of live foods be given to them. Hikari Cichlid Pellets
A male and a female Oscar will pair up and remain loyal to each other. A pair will readily spawn with the right water conditions. They will drop up to 2000 eggs on a cleaned surface and both will guard the eggs till they hatch. The fry will be kept in a pit and cared for by the parents. When breeding Oscars the larger the tank the better.
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