The smell of fish (fish odor) is not due to the fact that the fish died and then begin it’s decomposition but is due to trimethylamine, a compound that is volatile form after the death of fish, some proteolytic bacteria (demolition of protein structures) of the genera Achromobacter, Pseudomonas, Micrococcus, Bacillus putrefaciens Altreromonas and begin to colonize the meat.

The process continues on a regular basis over the period of edibility of fish, and this explains why the smell (fish odor) increases with time. Then stabilizes.

Cool?

The measure of the amount of trimethylamine is the most common for determining the freshness of the fish: if less than 5.10 mg / 100 g, according to experts FAO (UN Food and Agriculture) should be marketed.

The intensity of the smell indicates the degree of freshness and therefore quality fish.

Curiosity
It is not only the fish that lay decomposing on odor, there is trimetilaminuria, in people suffering from a disease that may have genetic origin, it spreads the same scent: in fact they are deficient in enzymes that transform trimethylamine, it is naturally present in the human body, in odorless compounds.