Metal cutlery is a no-no. Even then spoon. Plastic is the way to go. The sardines in a tin won't be allowed, due to the liquid in the tin. You could take the sardines out of the tin and put them in a plastic tub without the liquid. Solids are fine. Just make sure you've actually got solids. Pate and Brie, for example, are seen as a paste.
If security take any cutlery off you, ask the crew if they have a spare set.