Had 2 when I was a kid. I put a bunch of shredded newspaper in their tank and made like a little hut for them. They then gathered newspaper and took it into their hut. Make sure you get a friendly mouse. I had one that wouldn't mind getting handled and the other one would bite. I think the biter was a female and might have been pregnant. I was handling it one time and it bit me and I dropped it. Later one my cat got it. Don;t feed them any meat either. You can get them a little wheel or tubing or something for them to play/exercise in. Also mice are a lot quicker than rats. So keep in mind when handling or setting down or something.