The expression a red herring can refer to both a dried, smoked herring which has turned red during curing and a false lead or something used to divert attention from the wider issue. So are red herrings inherently deceitful and misleading fish?
Not exactly. The use of red herring to refer to smoked herring – as opposed to white herring or fresh herring – appears in the 15th century. By the 1680s, the fish was used by poachers to throw off a hunting party. They would walk between the hunters and the prey, dragging a red herring across the trail so as to distract the hunting dogs from the scent they were following. The red herring worked especially well since, because of its strong smell, the hunters used the fish when training the dogs. When the dogs then picked up the herring scent, they would follow that trail, giving the poachers the chance to catch the prey for themselves.
It wasn’t until the late 19th century that a red herring went from denoting the practise of throwing dogs off a hunting trail to throwing anyone off any trail. The expression to draw a herring across the track/trail was known by the 1880s. Now the phrase is most commonly associated with fictional murder hunts and whodunits where red herrings are used to keep the reader from solving the mystery.