it depends on the size of the snake, my babies get a pinkie or 2, then fuzzies for the larger ones, then large mice, then a couple of large mice, then rats, then if they are a big breed i'll move them onto guinea pigs and eventually rabbits, the only treat i give them is to starve them for 1-2 month every year (depending on breed/size) this keeps them in good shape and stops them become fat, it also seems to keep them regular feeders as none of my adults are fussy
