there shy, u can feed them catfish, shrimp, most any kind of ''freshwater fish'' beef heart for treat, if u feel u want to feed them live food, stay away from feeders, like gold fish, minows, carp(koi), they have no food value , and carry growth inhibators, mine like a convict here and there, they can get to 12 inches,they do better in schools of at least 3, a good tank size for 3 full grown RBP's is a 100 gallon, feed them as much as they will eat,they are messy eaters so make sure you have extra filteration, temp can be from 78 to 82 degrees, when there small they can be canaiblelistic, so keep a eye on them, probley the most commen Piranha for sale=beautyful fish, but very shy, if u were thinking they might be like chileds, there not, there differnt,