Best thing for feeding young oscars are frozen
brine shrimp AND/OR freeze dried
krill. High in protein and nutrients that helps with healthy growth and color enhancement. Ask your local petshop if they carry frozen fish food and look for Brine Shrimp.
Also look into the frozen food BEEFHEART. Great form of protein. Should be the main part of your fishes diet.
Once your oscars gets bigger [4" and up] you can supply a new diet of frozen SLIVERSIDES and SAND EELS. Good foods for large oscars that extends their longevity and overall health.
The brand that you should look for in all frozen/freeze dried fish food is SAN FRANCISCO BAY BRAND. You cant go wrong.
GOOD LUCK!