Fresh tuna smells like the ocean, not like a fish market.

Smell it first. Properly fresh tuna has a clean, briny scent — like a sea breeze, not a fishy stink. If it smells sour, ammonia-like, or just aggressively “fishy,” it’s past its prime.

Then look at the color and texture. Fresh tuna should be deep red to dark purple — almost mahogany. Brown or gray patches mean oxidation or age. It should also be firm and spring back when pressed. If it feels slimy, mushy, or leaves a wet imprint, skip it.

One exception: pre-packaged tuna that’s been gas-flushed can look red but still be old. Trust your nose more than your eyes here.