The Science Behind the Fishy Smell in Smelly Fish

You want to eat fresh fish. You want it glazed, or baked in parchment with fresh dill and lemon. You want the skin crisp from the broiler and the meat moist and juicy. Instead, you're looking down at a plate of stinky fish in all of its odoriferous glory. How could this smelly hell have been avoided?

Fresh fish, crustaceans, shellfish, etc., smell lightly of the sea when they're first caught, but they should never smell distinctly fishy. Unless you have an amazing fishmonger, or caught the fish yourself, the week-old cod you're buying from the supermarket will most likely reek. What causes it to smell so bad, you ask?

According to Don Glass from A Moment of Science, "fish tissue contains an odorless chemical known as triethylamine

oxide. Once the fish is killed and exposed to air, the chemical breaks

down into derivatives of ammonia, and therefore smells bad."

Yelp offers a few places with the best fishmongers, and here are some tips from the FDA to help make sure the fish you buy is a fresh catch.

  • The fish should smell fresh and mild, not fishy, sour, or ammonia-like.
  • The eyes should be clear and bulge a little.
  • It should have firm, shiny flesh and spring back when pressed.
  • It should not display darkening or drying at the edges.


quick tip for cooking fish that is more than a day old: Clean it with

fresh lemon juice. You can also soak it in milk, refrigerate it for an

hour, and rinse with water prior to cooking. This removes all traces of

fish stench because the acids in citrus and

milk neutralize the bases from the triethylamine.

Getting your hands on fresh fish is more than a luxury. The

FDA warns that anything but fresh might have high levels of scombrotoxin,

which can lead to illness. It's important to make the effort to care

about what you eat, or it could come back to bite you.

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Anais Alexandre