I was a few months in europe ( 4 months) for work reasons, by the time I left had like 25 cans of tuna I bought for my diet I was following, do you think they are still consumable? they were in the fridge all this time.
Canned tuna that is not opened has a shelf life of 20+ years. That's why it's often included in survival ration packs. It doesn't go bad for a really long time.
Once you open the canned tuna, it's exposed to air which will allow bacteria to grow. It will have a shelf life of about 7 days once opened in the fridge.
Opened canned tuna is pretty much the same thing as any freshly cooked fish. It will have the same expiration date and needs to be stored the same way.