oarfish

noun, plural (especially collectively) oar·fish, (especially referring to two or more kinds or species) oar·fish·es.

1. any long, ribbon-shaped, silvery fish of the genus Regalecus, of deep tropical waters, having a red dorsal fin along the spine that rises to a crest, and reaching a length of 30 feet (9 meters).

noun plural -fish or -fishes

1. a very long ribbonfish, Regalecus glesne, with long slender ventral finsAlso called: king of the herrings