If opened, 1 month on shelf & 6 months kept in refrigerator.
Because of the acidity and salt content, if kept in the refrigerator it should last for 3 months safely.
No. You should not keep tuna in the can after opening.
1 can diced tomatoes. 1 can plain pasta sauceadd whatever you want to it. I prefer to add onions and garlic.stick it in the fridge.
close it....