Tinned fish can last up to five years without spoiling. However, the opposite is true for opened cans of tuna, as they will be susceptible to spoilage if left out on the counter.
According to the U.S. Department of Agriculture, tuna can last up to four days in the fridge. Waiting any longer puts you at risk of ingesting foodborne pathogens.
Place your food in an airtight container to ensure it does not dry out or lose its flavor. This will keep tuna from becoming cross-contaminated and prevent it from spoiling.
While many foods tend to last in the freezer, canned tuna is not one of them. This tends to ruin the textures of most canned goods, leaving you with a mushy product once it thaws.
Once your tuna is in the fridge, watch for signs of spoilage. Use up leftovers within four days to minimize chances of food poisoning.