Catfish

Catfish keeps 1–3 days refrigerated and 2–3 months frozen. Despite being a freshwater fish it is moderately oily, which is why its freezer window matches salmon's rather than cod's.

Store it cold and covered, patted dry, ideally over ice. US catfish is overwhelmingly farmed in ponds and processed quickly, so counter fillets are often genuinely fresh rather than thawed-from-frozen — worth asking, since it changes whether you can freeze it at home.

Catfish fillets are thick and dense, so they take longer to chill through than thin whitefish. Give a fresh purchase time on ice before assuming it is at refrigerator temperature throughout.

Wrap airtight for the freezer. The fat content means oxidation, not dehydration, is the limiting factor.

Catfish sits in an unusual middle ground: a freshwater fish with enough fat to behave partly like an oily marine one.

The fat — around six to eight percent in farmed channel catfish — is what caps the freezer window at 2–3 months rather than the 6–8 that lean whitefish get. Those fats oxidize at 0°F, slowly but steadily, producing stale, painty flavors while the fish remains perfectly safe.

Being freshwater, catfish carries little trimethylamine oxide, so it does not develop the sharp ammoniac smell of aging saltwater fish. Its spoilage smell is muddier and more sour, and it is easier to miss. As with tilapia, this makes the nose a less reliable instrument than usual — go by the purchase date.

The "muddy" flavor catfish is sometimes accused of comes from geosmin, a compound produced by pond algae and absorbed into the fat. It is a water-quality issue present from the moment the fish was harvested, not a sign of age, and modern US catfish farms test and purge for it.

Discard on a slimy surface, mushy flesh that holds a dent, or a sour smell.