Salmon

Salmon keeps 1–3 days refrigerated and, as an oily fish, only 2–3 months frozen — a quarter of what lean whitefish manages. Store it over ice in the coldest part of the fridge, in a covered dish rather than in the paper it came in.

For freezing, wrap tightly and press out every bit of air. The fats that make salmon worth eating are exactly what limits its freezer life, and they oxidize on contact with oxygen even at 0°F. Vacuum sealing roughly doubles the useful window.

Skin-on fillets store better than skinless: the skin is a natural barrier against moisture loss and oxygen. Freeze skin-on when you have the choice, and remove it after thawing.

If you are planning to eat salmon raw, buy fish explicitly sold for that purpose. FDA guidance for parasite destruction requires freezing at -4°F for seven days or -31°F for about 15 hours — temperatures a home freezer, which typically runs at 0°F, cannot reach.

Salmon is an oily fish, and it fails by two mechanisms running in parallel.

Bacterial and enzymatic spoilage proceeds as it does in any fish, converting trimethylamine oxide into the sharp ammoniac compounds that signal a fish is past it, and softening the flesh as its own enzymes digest the muscle structure.

Fat oxidation is the second, and it is why salmon's freezer window is 2–3 months against cod's 6–8. Salmon is rich in long-chain omega-3 fatty acids, which are highly unsaturated and therefore highly reactive with oxygen. That reaction is chemical, not biological, so freezing slows it but never stops it. Frozen salmon stays safe indefinitely at 0°F; it simply develops a stale, painty rancidity that no cooking will hide.

Salmon's orange color comes from astaxanthin, a carotenoid pigment from its diet, and it fades with age and oxidation. A dull, graying fillet is a reasonable quality signal. But it is not a safety test, and farmed salmon's color varies with feed regardless of freshness.

The reliable signs are a slick or sticky film, flesh that stays dented when pressed instead of springing back, gaping between the muscle flakes, and a sour or ammoniac smell.