The Regalecus glesne, known as the King of Herrings or Giant Oarfish, was found dead in the small fishing village of Bovallstrand on Sweden's west coast, about 90 kilometers (56 miles) from the Norwegian border.
This is the wiki page of the Oarfish.
The rarely seen regalecus, the world's longest bony fish, can reach up to 12 meters.
Sightings of the fish are believed to have inspired tales of sea serpents.
Eriksson, a retired engineer and amateur fishing, made the unusual discovery on Saturday when he returned to the boat shed with Bovallstrand, on the west coast of Sweden.
Here's video of the Giant Oarfish in action, courtesy of The Discovery Channel:
It is not known what the museum is going to do with the fish at this time, but they are currently studying it and finding out more about the species. They can grow up to 50 feet long and are saltwater fish that normally stay far below in the depths of the ocean.