In music, a "mordent" is a little figurative turn of notes, where you very quickly play a note next to the main note - like taking a little nibble of an adjoining note. You hear it all the time in Baroque music.
I put "The fish aren't biting today." and got it right. I don't always like to change the word order, but this sentence is such a cliché in English that I wanted to say it exactly as we usually say it.