Rats are individuals, and different rats prefer different treats. Try and stick with healthy foods which include diced fruit and vegetables. A lot of rats will go bonkers for peas, or foods that you would find tasty such as small cubes of mango, apple, pear, kiwi, melon, or banana. To start training your rat, consider using a clicker. The first step is to get the rat to link the click-clack noise to getting a treat, then you mark the behavior you want by pressing the clicker.