How long does tuna last?
Unopened, it keeps in the cupboard for about 3 years. Once opened, in the fridge for about 3 days.
This refers to: Canned tuna.

Shelf life of tuna at a glance
| Storage | Unopened | Opened |
|---|---|---|
| Cupboard | 3 years | – |
| Fridge | – | 3 days |
Move leftovers from an opened can into a covered container and eat within 3 days. Fresh tuna keeps only 1 to 2 days in the fridge.
Past its date does not mean spoiled
These are guide values for food stored correctly. A best-before date is not a throw-away date: many products are still fine after it. Check how it looks, smells and tastes. Mould, an unusual smell or a bulging can are reasons to throw it away. A use-by date is different: do not eat the food after it.