3 winters ago, field mice got into the garage, probably when the previous guy was moving out. I was fortunate, because I was able to catch them all, and they were all males. However, I discovered they were there because one drowned in a tank.
If anyone's inclined to post about this happening to them, immediately do a 95% water change. Then do another. I wonder if mouse fleas qualify as live food.
It's an issue in my environment because rodents want out of the cold. The deer are back to staring in the windows of the fishroom, but they aren't getting in no matter how sorry I feel for them.