You want to feed something that is about the same size as the widest part of the snake once a week. A good size meal will live a mild, but noticable lump in the belly. If you arent getting much of a lump then its time to move up. Most baby bps are able to eat full grown adult mice within a couple of months. This is the main reason the rat suggestion came up. Within a short period of time a single adult mouse will not be an adequate meal for you snake, and its just easier to feed a single appropriately sized rat once a week then 3 or 4 mice.
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