Good question, my ball is about 22'' and i thought about feeding him 2 mice last night (Tuesday). I feed him every 4 days and he strikes and kills the mice in less than a minute each time, he knows whats going on when i put him in the feeding box and i have only had him 9 days, he has eaten 3 times already (he ate the first night i brought him home) but after i let him choke down that first mouse last night it left a nice size lump in him, so i figure i'll just wait and just feed 1 mouse every 4 days, I don't want to over feed him... He is a GREAT eater so far!!