The King of Herrings is neither a king, nor a herring. It is not even a close relative to herrings. However, it is a rather large fish also known as the Giant Oarfish (or Regalecus glesne).
The first fish come as recent as mid 18th century Norway, but many claim that it is responsible for early tales of sea serpents. With its size, there can’t be much surprise. While Giant Oarfish are only a couple feet high, reports have shown that the fish can reach 56 feet long! This makes it the world’s largest bony fish.
Sightings of the King of Herrings are fairly rare, this is due to the fish’s habitat. 1000 feet to as deep as 3000 feet under the ocean. A majority of the fish that have been found were dead or in the process of dying. Seeing them alive in their own habitat doesn’t happen often, so this video (from the Discovery Channel) of a live R. glesne is quite a find:
More commonly, fishermen will accidentally bring the fish up or they will wash ashore on their own. Most recently, a 3.5 meter long Giant Oarfish was caught off the coast of Taiwan. It was seen as a bad omen by some, as other Oarfish have been found shortly before earthquakes.