feeding and also scale rot

Hey i jus have a few questions, my ball is about 3 1/2 ft long, his name is sgt pepper, and when i buy a rat for him he doesnt seem interested even if i leave it in the box for him to smell it for a while, i get a rat once a week and i was wondering if i should feed him every 2 weeks now because hes getting larger than when i first got him from a friend, also my friend said he had scale rot in the past and i would like to know how to treat and prevent it if it happens again, any advice would be great
Tickles