Hey, I have been reading on this site over and over people asking what to feed their piranhas. I am by no means an expert at raising piranha, but I was damn successful. The key is you have to keep in mind that you are raising fish that you are trying to get to be aggressive. I got my p's at 1" and I only fed them live food. I never had a problem with disease, and if they didn't like what I was giving them, they just didn't eat. When you have small p's feed them guppies. Then graduate them to Red Rosies, then to gold fish. It is important not to overfeed them also. These fish are not to be pampered and coddled, it just makes them soft. I made a point, and I was just lazy also, not to feed them for a few days and even a week or two at a time. This makes for hard, tough, p's. The first time I threw a mouse in they devoured it and it was so cool. Then we threw another one in like 3 days later and it drowned. For this behavior, and as punishment, I didn't feed them for 2 weeks. I even once fed them a hampster, which they absolutely ravaged. The key is to keep them accustomed to live food and keep them hungry. Also, forget about this overcrowding rule in tanks people talk about. As you saw from the video we had six p' all 6"-7" in a 55 no problem. This is just my suggestions on how to raise p's and get results like we did. BTW, it also helps to play rap music and have a phatty handy.