How big is he? If you got a hopper mouse and left it in the enclosure overnight, they pose no harm to your snake at all. I know some of mine will not eat for sometimes hours after I place the f/t rat in. They wait until all the lights are off and we are sound asleep...of course if he's big he'll need more than a hopper mouse on a regular basis, but you may be able to try a few in his tank overnight to get him feeding consistently...