You should go with a rat fuzzy! Rats are a better choice because you can get one feeder that is the right size all their lives. With mice, balls outgrow them fast then you have to feed multiple mice every feeding. My friend has an adult female(1600 grams) and she eats like 6 mice every week! He has another female that eats just one medium rat a week! Mice cost $8 a week and rat costs $3.50 a week! Big difference! There is nothing wrong with feeding mice and the snake will grow fine! It's completely up to you! I go with the thickest part of the snake not 15% of weight but that's how I like doing it! Good luck!