Heard of the saying "something smells fishy"? Have you noticed how a fresh fish smells different from one that is not so fresh? Yes, once again it is chemistry that is the reason behind this.
The cause of the stink
Fishes smell because of a natural process of decay. Bacterial enzymes attack the flesh of the fish. This triggers an oxidation reduction reaction. The muscle of the fish contain a substance called trimethylamine oxide (TMAO) which is broken down by decomposition. The result is trimethylamine and dimethylamine. The mixing of these two amines results in that characteristic fishy smell. In fact, it is the presence of trimethylamine that is used as an indicator of how fresh a fish is.
Do you know you can use lemon, vinegar and baking soda to reduce the smell of the fish?
Removing the smell
If you do have a very smelly fish and need to remove the fish smell, then chemistry can come to your aid once again. Using lemon, vinegar or baking soda will reduce the smell of the mixing amines. Amines are alkaline based and lemon juice is acidic in nature, thus mixing the two neutralizes the effect of each other. This is why lemon is added to fish preparations to remove the strong smell of fish.