Piranhas aren't very picky about food. I've feed mine a wide variety of foods, such as blanched zucchini, brine shrimp(when they were juveniles),beef heart,krill,raspberries,strawberries,spinach leaves,earthworms,crayfish. The veggies and fruit they will nibble on, but usually won't eat it all. I have had the most success with krill,beef heart,and chicken.