i always offer a rat pink or pup first depending on size of the hatchling. If they take it then good, if not I offer a mouse hopper right after i take out the rat, this usually triggers a very good feeding response in hatchlings. If not then I offer mouse hopper the next day or 2 days after. hopper mice will usually not harm your snake, but its still better to keep an eye on them and not leave them in there too long.