Description & Behavior

Oarfishes, Regalecus glesne (Ascanius, 1772), aka giant oarfishes, king of herrings, king of the herrings, oar-fishes, ribbon-fishes, ribbonfishes, are one of three known species of the oarfish family (the others being the Oarfish and Streamer fish). They may be the longest bony fish known with reliable records of 8 m long specimens and reports of 11 m long individuals weighing 272 kg though most specimens measure around 3 m. The Giant oarfish has a distinctive concave head profile with a small protrusible mouth with no visible teeth and 33 to 47 gill rakers. Their eyes are relatively small for their size. They lack scales and their skin is instead covered by a layer of silvery guanine. Indeed the coloration of this fish is predominantly silver with bluish streaks and black vertical streaks and spots. Their body is extremely long and laterally compressed tapering to a point at the end of their tail. They have a reddish–pink dorsal fin that extends from above their eyes, along the length of their body, to the tip of their tail and contains around 400 soft rays. The first 10-12 anterior dorsal rays are organized into two crests of elongated and ornamented rays with reddish spots and flaps of skin to the end of each ray giving the distinct impression of the fish sporting a Mohawk hairstyle. Their pectoral fins are very small while their pelvic fins consist of single extremely elongated and ornamented fin rays which may be used for taste reception. They lack both anal and caudal fins.

Giant oarfishes are unusual in that they appear to swim in a vertical orientation with their head pointed towards the surface and their tail pointing down towards the seafloor. In this position it appears that their extensive dorsal fin provides propulsion. The fish has gelatinous flesh which makes it unpalatable for human consumption (thankfully). Giant oarfish are thought to be originators of the tales of sea serpents though its common name comes from the appearance of its oar-like pelvic fins. Additionally, these fish hold the other common name ‘King Herring’ which is derived from their dorsal crests giving the appearance of a crown and the belief that they led schools of herring.

World Range & Habitat

Oarfishes, Regalecus glesne, are found throughout the world’s temperate and tropical oceans though their range does not extend to the colder polar waters of the Arctic and Antarctic. They can be found in depths of 15 to 1,000 m, occupying the epipelagic and mesopelagic zones, though they are mainly found at 20 to 200 m. Sometimes sick and dying specimens may be observed swimming near the surface. They are primarily solitary fish and do not show schooling behavior.

Feeding Behavior (Ecology)

Oarfishes, Regalecus glesne, are filter feeders. They orient themselves vertically within the water column which is theorized to allow them to spot the silhouettes of prey items. Then they use their protrusible mouths to suck in prey items including plankton, squid, fish and euphausiid crustaceans which are then strained out of the water by the gill rakers. There is some speculation that they may also steal food items from siphonophores.

Life History

Oarfishes, Regalecus glesne, are oviparous broadcast spawners and spawn in warm waters between July and December. After fertilization its large eggs pelagic eggs (2-4 mm) remain near the ocean’s surface until hatching after about three weeks. The resulting larvae have the appearance of miniature adults and feed on plankton until they mature.

Oviparous: produces eggs that develop and hatch outside the body of the female.

Conservation Status & Comments

Oarfishes, Regalecus glesne, are currently evaluated as a species of least concern by the IUCN red list as it is not a commercially valuable species and has a wide distribution though it is unclear how the proliferation of micro-plastics within the water column may affect the welfare of this filter feeding animal.

References & Further Research

Collette, B.B. 2015. Regalecus glesne. The IUCN Red List of Threatened Species 2015: e.T190378A76701576.
McGrouther, Mark. “Oarfish.” The Australian Museum,
Bester, Cathleen. “Oarfish, Regalecus glesne”, Florida Museum of Natural History,
Bourton, Jody. “Giant bizarre deep sea fish filmed in Gulf of Mexico”, BBC Earth News,
Boyd, Stephanie. “King of Herrings”, Texas Saltwater Fishing Magazine,

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