There's a lot of pellet food on the market these days that is targeted for great growth and color in cichlids. I think that its all just a matter of preference to you and what is available/affordable to you. For me, I use a few different kinds of pellets/stick formulas as well as worms/insects for treats. In my experience though, you should not have any trouble growing an oscar. They eat lots and lots of pretty much anything. Just keep up with the water changes!