> I'd trust any well established sushi place with ahi and salmon than I would my own fridge.
FYI, in the US it is common to mummify fish with carbon monoxide. It preserves the fish's color despite age. The best way to stop oxidation is to add a reducing agent!
I don't think CO is a problem, but it is a hack restaurants use that consumers are unlikely to be aware of which masks the visual indications of freshness.
AFAIK this is specific to tuna and done by places like fish markets, that publicly display it. A restaurant would most likely be getting it frozen and vac packed.
FYI, in the US it is common to mummify fish with carbon monoxide. It preserves the fish's color despite age. The best way to stop oxidation is to add a reducing agent!
I don't think CO is a problem, but it is a hack restaurants use that consumers are unlikely to be aware of which masks the visual indications of freshness.