Adam, if it's an adult female rat, you may have hordes of rats soon. Selling rats is an easy, but stinky way to make money.
Raising rats, but more mice and catching and selling snakes, turtles, amphibians and trapdoor snails, is how I got most of the money my girlfriend and I bought food with in college. I also graduated in 3 1/2 years instead of the normal 4 or 5 years, by turning my mice raising into a 6 credit, independent study, Anthropology project.
Keith
I used to raise rabbits like that and would sell them to snake people. I couldn't keep enough, and none went to waste. Every one that died as a kit I'd freeze it and sell them when I got a dozen or so put back. If I hadn't been promoted at work and lost all my spare time I'd still be doing it.
And it was my final project as a senior in college, too! Wrote a business plan, financial statements, the whole deal.