Other contributors have said "Do piranha eat eels?" is the same question as "What do piranha fish eat?" If you believe that these are not asking the same thing and should be answered differently, click here
Piranhas would eat normal fish food, but they are carnivorous, and woulld like meat products, and their favorite is live bait. (Note: I'm not trying to gross you out or something with the last remark... it is actually the truth.)
Actully, piranhas usually won't eat fish. They may eat them if they are already dead, though. Piranhas typically eat animals such as duck that are floating above the surface, which may appear to be...