I've had 5 bps, and all of them were eating live when I purchsed them. I've had no trouble switching them to f/t. In fact, each of them have taken a frozen rat first feeding with me. As far as age, I've had one 4 weeks old that switched fine as well as older balls. Recently got a new 7 month old and he switched fine also. That being said some will only eat live and if I had one like this obviously I would feed live. But don't be afriad to try f/t, most do okay. I think presenting it the right way and the right temp is key.