red herring

noun
  1. 1

    A herring that is cured in smoke and brine strong enough to turn the flesh red; a type of kipper.

  2. 2

    A clue, information, argument etc. that is or is intended to be misleading, diverting attention from the real answer or issue.

  3. 3

    A red herring prospectus.

Source: https://en.wiktionary.org/wiki/red%20herring