Oarfish

산갈치(대왕산갈치)

The longest bony fish, reported at up to about 8 m. It lives hundreds of metres down, so living ones are rarely seen, and its silver ribbon body with a red crest fin may be behind old sea serpent stories.

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At a glance

Class: Fish
Diet: Meat eater (carnivore)
Conservation status: Least Concern (IUCN LC)
Habitat: deep sea, open ocean

Quick answers

Where does the Oarfish live?

It lives in deep sea, open ocean of the Pacific, Atlantic and Indian oceans.

What does the Oarfish eat?

Its diet: meat eater (carnivore).

Is the Oarfish endangered?

It is listed as Least Concern (IUCN LC).

Oarfish are the three species of large and extremely long open-ocean fish in the small family Regalecidae: the giant oarfish (Regalecus glesne), Russell's oarfish (Regalecus russelii) and the streamer fish (Agrostichthys parkeri). They live in areas from temperate to tropical oceans, but people rarely see them. The giant oarfish is the longest bony fish alive, growing up to about 8 metres.

The streamer fish reaches about 3 metres, and the largest recorded Russell's oarfish was 5.4 metres. Oarfish are silver with small dark spots, have no scales and no swim bladder, and their long, ribbon-like bodies taper to a fine point. Their flesh is gelatinous and not well regarded for eating, and the larger species are fished on only a small scale.

Built like a ribbon

A dorsal fin begins above the large eyes and runs the whole length of the body, with about 400 rays. The first 10 to 13 rays stretch into a trailing crest with reddish spots. The pelvic fins are also long and oar-like, and the anal fin is missing completely. The name oarfish may come from the flattened body or from the old, now discredited belief that it rows with its pelvic fins.

Oarfish often drop the tip of the tail, probably to escape predators, and the tail does not grow back. In 2001 one was filmed alive in the Bahamas swimming by rippling its dorsal fin while the body stayed straight.

Rare glimpses

Most of what we know comes from stranded fish, accidental catches and a few chance meetings. In 2008, scientists filmed an oarfish in its natural home for the first time, in the Gulf of Mexico, estimated to be five to ten metres long. The deepest verified record is 463 to 492 metres.

Oarfish feed mostly on zooplankton, straining tiny shrimp-like animals from the water, and also take small fish, jellyfish and squid. They sometimes swim upright, which may help them see prey silhouetted against light from above. They seem slow to flee from remotely operated vehicles, suggesting they have few natural predators.

Sea serpents and omens

Their size, their rarity and their habit of lingering at the surface when sick or dying make oarfish a likely source of old sea-serpent tales. The family name Regalecidae comes from the Latin regalis, meaning royal.

In Japan, the slender oarfish is called Ryugu-no-tsukai, the messenger from the sea god's palace, and is said to warn of earthquakes. After the 2011 Tohoku earthquake, many pointed to the 20 oarfish that washed ashore in 2009 and 2010. A study in 2019, however, called the link between oarfish and earthquakes an illusory correlation.

Fun facts

Sightings of oarfish at the surface may lie behind some old sea-serpent stories.
Oarfish are rarely caught alive.
Their flesh is jelly-like.
They are a probable source of historical sea-serpent tales.
As of August 2024, only about 20 oarfish sightings had been recorded along California's coast since 1901.