Hamsters require a more basic diet and should be fed hamster food. This should be fed with small amounts of fruit and vegetables which should be offered in very small pieces.
Rats require a low fat diet, high fibre diet. Specially formulated rat pellets. Rats also benefit from small amounts of dark leafy greens and/or broccoli. Don’t be alarmed if your rat appears to eat very little, due to their small size they only require very small amounts of food on a daily basis.
Mice have essentially the same diet as rats but in even smaller quantities. They can also have seeds and grains, but beware the high fat content of these treats!