What causes dead fish to stink so bad?
#109655. Asked by star_gazer. (Oct 10 09 10:53 AM)
The culprit seems to be TMAO.|
The principal smell contributing to “fishiness,” says McGee, is a compound called trimethylamine, or TMA. It is derived from trimethylamine oxide, or TMAO, which is not in itself objectionable. TMAO is one of several amines and amino acids that ocean creatures accumulate inside their cells to buffer them against a fatal influx of sea salt. (Seawater is 3 percent salt; the optimal level of dissolved minerals in animal cells is about 1 percent.)
Once a fish is dead, TMAO is gradually converted to TMA by bacteria proliferating on the surfaces of the fish. (Freshwater fish like ayu live in an environment less salty than the inside of their cells, so they don’t accumulate amino acids and amines. Their flesh is mild tasting and slower to turn smelly.)
As for truly spoiled fish, let’s just say that by the time proteins are being broken down into skatole, putrescine, cadaverine, and hydrogen sulfide, you probably won’t want that fish in your mouth.
Also see Question #91678:
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