I would not give mice or rats as a daily food item, it could cause them to get a fatty liver. Try not offering them to your water monitor, until it starts eating what is better. I know my monitors won't look at crickets anymore, is it still eating the roaches? I have found when I started giving roaches they didn't eat much else. If not, just stop giving the rats and mice for awhile, the monitor will eat again, they can be fussy sometimes.