Welcome to the site Taker, Personally I have never used feeders for my Oscar's. I know its a natural way to feed them, but there is so much quality food out there to be had. Touch wood I have never had any disease in my Oscar tanks over the years and I put that down to good diet and clean water. I use Hikari cichlid gold pellets as a staple diet, with Bloodworm, earthworm, Crickets, Prawn or Mussel as treats. You could use Convict fry, but you would probably need three pairs, depending on how many and how big your Oscar's are.