Tuna out of a can is
not good, it has alot of sodium, and milk, cats usually can
not digest and it can give them diarrhea..also Grapes, raisins, chocolate can be very bad for your cat.
Please consult with your vet as what cats should not eat, only warning is alot of vets recommend Iams or Science diet for animals as the choice for feeding but I believe there are alot better cat foods out there as I listed above...
What you need to look at is the first five ingredients..