Real fast. What's his temps on the hot and cold side? Ambient temps. And humidity.

And if he's a mouser. Try feeding 2 mice a week at least. I would look at environmental factors to see why he won't eat as much. Along with other things.

Not trying to bash you at all. I hope I'm not coming off that way. He's just not getting a whole lot of food. And I'm just trying to look out for his health. Thanks for the replies.