Oarfish

Oarfish are long, ribbon-shaped marine fish in the family Regalecidae. They live mainly in the open ocean and are rarely seen near the surface.

Regalecidae: Regalecidae is the family of elongated, ribbon-shaped fishes that includes oarfish. This is the taxonomic family to which oarfish belong.
Oarfish swimming: Oarfish swimming is locomotion powered largely by rippling the long dorsal fin while the body remains comparatively still. This fin-driven motion helps explain how a ribbon-shaped fish moves without broad body undulations.
Giant oarfish: The giant oarfish is a species of exceptionally long, deep-water fish in the genus Regalecus. It is the familiar example behind many accounts of the family's extreme length.
Deep-sea biology: Deep-sea biology studies organisms living in the ocean's deep-water environments. Oarfish illustrate how difficult it is to study animals that rarely reach accessible depths.
Lampriformes: Lampriformes is an order of mostly marine fishes that includes oarfish and ribbonfish. Oarfish belong to this broader order of deep-sea and open-ocean fishes.
Oarfish feeding: Oarfish feeding involves taking small planktonic animals from the water, including krill and other crustaceans. Their diet links their movement through open water to the distribution of drifting prey.
Ribbonfish: Ribbonfish are elongated lampriform fishes in the family Trachipteridae, distinct from oarfish. Their similar shape leads to frequent confusion, but they belong to a different family.
Marine telemetry: Marine telemetry tracks aquatic animals using electronic tags that transmit or store location and movement data. Tagging could clarify the routes and depth patterns that sightings alone cannot establish.
Pelagic zone: The pelagic zone is the water column of seas and lakes, away from the bottom and shore. Oarfish spend most of their lives in the open-water habitat.
Plankton: Plankton are organisms that drift in water and cannot swim effectively against currents. Planktonic animals make up much of the documented prey of oarfish.

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LancetfishCompared with: Both have strikingly elongated bodies, but oarfish belong to a different fish lineage.