Feeder fish is one of the biggest issues in what to feed your O. I'll admit, it is fun to watch you oscar chase down a feeder and suck it up. Now you have to ask yourself, "Is it worth the pleasure?" There are many risks that come along with feeding live fish to your oscar. Diseases is one of the biggest risks. HITH (hole in the head disease) is very common among oscar owners. IMO feeders is the most common reason for HITH. Feeders are not part of thier natural diet in the wild. Feeders have a lack in nutrition unlike pellets which contain many of the vitamins and such that is important for oscars. Frozen foods make a great treat once every other day or so. Also, crickets and ghost shrimp are fun to watch them eat and come with less risk for disease.