By Harold McGee
Most fish in U.S. markets are sold precleaned and precut. This is certainly convenient, but it also means that the scaled and cut surfaces have been exposed to the air and bacteria for hours or days, drying out and developing off-flavors. Preparing fish at the last minute can give fresher results. Both whole fish and pieces should be rinsed thoroughly in cold water to remove fragments of inner organs, the accumulation of odorous TMA, other bacterial by-products, and bacteria themselves.