I was feeding my Oscars Hikari Gold during the day and fresh prawns and peas at night and they no longer want the prawns so it can work the other way too. I have moved on to Crickets and meal worms instead of the prawns but they still can't get enough of the pellets!
My Oscars would eat small children if they thought they could get their mouth around one. I would cut chunks of raw shrimp if you though it looked like he was having troubble getting it down.