Hey everyone
I've read a lot that you're supposed to compare the weight of the prey with the weight of your BP to choose which size is appropriate, but how do I know what weight it should have? Sorry if I repeat a thread but I somehow don't find anything about it.

My boy is 3-4 months old and weighs about 120gr. When I got him about a month ago the breeder told me that they fed him a hopper a week. Meanwhile, I give him 2 hoppers every 5-7 days.
What prey should I offer him according to his age and weight?