I am not of a mindset they have to be kept in a cage either and can roam free. Poisonous, sick, or injured ones, or if you have children are another story though. I used to have snakes, snake proofed the house, and provided heat sources (large hot rocks and lamps) throughout they could go to or perching stations on windowsills for sunning. Freaked people out when they came over but not so far fetched IT; takes a lot of diligence and responsibility to do this however.

So what have you named him/her? Fish can work just as well as mice for some species if the mice repulse you, but a varied diet would be better.