If you want him off dagus and asf's and other specialty food, I would not get him anymore of them.
He's big enough and old enough that he could easily go 10 months with no food (if he's healthy overall). If he's not losing weight, he does not need to eat in any sort of urgent manner.
If he's eaten rats or mice in the past, and that's what you want him eating in the future, I would just offer him either of those every two weeks.