Jugger - Many feel that using a piece of raw shrimp will do just as well to start the cycle, as using live animals. Many feel that it is just more humane that way. It serves to prevent any fish from being stressed out and getting ick or other illnesses while cycling the tank. The shrimp starts the cycle by breaking down into ammonia. I personally started my 90 this way and didn't add anything live for nearly 2 months. I used a very large prawn, which worked great, but I should have placed it in a micron bag or nylon because once it breaks apart it is a pain to clean.
Thomas