I think adult mice are usually around 25 grams, but not that sure. If that is true, it is pretty big for Thor, usually you want to feed ~10% of their weight. If adult mice are pretty much your only option, I would probably extend to at least every 7 days. As far as I know, no lighting is even necesarry, though keeping a day/night cycle is preferable, but requires no special bulbs. Hope this helps;