Muet comme une carpe

Channel your inner fish and don't say a word.  Muet comme une carpe - mute as a carp - is today's curious French expression and it requires silence.

The expression is used to describe someone who refuses to share information about a certain topic.  In other words, they choose not to speak, even though you suspect they could potentially contribute to the matter at hand.  And that is annoying, at least to some extent.

We usually see the expression with the verbs être - to be - or rester - to stay.  It makes sense: either one is, or stays, completely silent.   Note that this expression agrees with its subject in gender and number, so the adjective muet may become muette, muets or muettes.  Similarly, une carpe could become des carpes.

The closest English translation that comes to mind would be tightlipped, or tight as a clam, as the British would say.  Quite fitting since both carp and clam live in the water and tend to stay pretty quiet to a human ear.  The clam image adds the powerful metaphor of a mouth shut tight.  What about the carp, then?

Origin

Muet comme une carpe dates back to 1612 when French writer François Rabelais coined its original form muet comme un poisson - mute as a fish.  The story is quite simple: fish don't talk.  Like the best secret-keepers, they keep quiet.  At least, from a human perspective.

It's unclear how the expression went from a generic fish to a carp.  However, linguists offer some interesting observations.  First, in regions far from seas and oceans, the word carp was often used as a generic word for fish since carps used to be - and still are - the most common freshwater fish in Europe.  Some also suggest that the switch was due to the carp's tendency to lift its head out of the water, mouth agape, as if it was about to speak but then changed its mind and kept quiet.  How aggravating.  Almost as much as a clam shut tight.

Examples

Durant toute l'affaire, elle est restée muette comme une carpe.
Throughout the whole affair, she stayed tight as a clam.

L'inspecteur avait beau poser des questions,  les témoins restaient tous muets comme des carpes.
The inspector kept asking questions but witnesses were all silent as the grave.