From what you say you have, I suggest rats. But breed them AWAY FROM YOUR HOUSE! The stench is overwhelming from 2 pet rats. Also, in your problem with your mouser,try finding a white rat live or frozen. If it's alive, gas it with Co2. Mouse or rat shouldn't matter. Color however, has been known to cause some picky eaters to go off feed. it might be to small to eat a rat. Try a small white rat first. Maybe a rat pup or weanling.