This is what I meant when I said Rats are more nutritional than mice. They're denser and provide more calories. I learned this from my breeder. In terms of names and sizes, my pet store sells rat pups that are the size of adult mice, so rat pups are roughly 20-30 grams at this store. Their small rats are a step up from that and are closer to 50 grams.
So gameonpython, you're doing it right if you're going by the 15% rule. Just make sure when you are weighing your Marshall, weigh him after he poops because that is a more accurate and realistic weight of your snake. My Akeda weighed something like 265 grams, and then he pooped and dropped down to 237.
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