I would also be curious what he was started on, mice or rats. From what I've read specifically on carpet pythons, once they're started on a food source, they can be nearly impossible to switch. A couple years ago I rescued an adult IJ carpet who came to me as a mouser. He was being fed 5 adult mice in one sitting every month or two. I got him on 5 mice every 10 days and he's been fine with that, and a very aggressive mouse eater. I then tried to switch him over to rats since that's what I'm breeding. I tried EVERY trick I could think of from live, PK, brained, prescented, etc and my carpet python doesn't even look twice at a rat, but he'll strike a mouse within 5 seconds every time...