Opened tuna keeps about three days in the fridge.

Three to four days.

That’s the USDA recommendation, and it’s a good rule. After that, the texture starts going downhill and the risk of spoilage creeps up. But here’s the thing: canned tuna is already cooked and sealed, so once you open it, you’re dealing with the same timeline as any cooked protein.

Trust your nose. If it smells off, tastes metallic, or looks slimy, toss it. A sealed container helps it last a day or two longer than leaving it in the can.

You’re probably not going to forget about it that long, but if you do, don’t chance it.