Animal
Giant oarfish
The giant oarfish is a very, very long, silver fish shaped like a ribbon. It has a red fin all along its back. It lives deep in the ocean, so people hardly ever see one alive.
The giant oarfish is the longest bony fish in the world: it is usually about 3 meters long, and some have been reliably measured at 8 meters. Its silver, ribbon-shaped body has a red fin running all the way along its back. It lives in the open ocean, often hundreds of meters down, and drifts upright, head up, while it feeds on tiny krill.
Regalecus glesne (family Regalecidae) is a rarely seen fish of the epipelagic and mesopelagic open ocean, recognized as the longest bony fish. It swims by undulating its long dorsal fin, often hangs head-up in the water, filters krill with toothless jaws and gill rakers, and can shed the rear of its body (autotomy). The IUCN lists it as Least Concern (2015).
Photo: Gary Dickson, CC BY 4.0, via Wikimedia Commons
Meet the giant oarfish
The giant oarfish is a long, flat, silver fish.
It looks like a long ribbon. A red fin runs all along its back. It lives far out in the deep sea.
The giant oarfish is the longest bony fish alive. Most are about 3 meters long, and the longest reliably measured was about 8 meters, nearly as long as two cars parked end to end.
Its body is long, flat and silvery, with darker streaks and spots, and it has no scales. A pinkish-red fin runs along its whole back, and the first rays of that fin stick up in a red crest on its head. It has long, thin red fins under its head too.
Regalecus glesne is a ray-finned fish (class Actinopterygii) in the oarfish family, Regalecidae, order Lampriformes. The IUCN, the Australian Museum and FishBase describe it as the longest bony fish; sources differ on how long it can get. The IUCN gives a maximum size of 17 meters, while the Australian Museum says 8 meters is reliably documented and specimens of up to 17 meters have only been reported. FishBase gives a common length of 3 meters and a heaviest published weight of 272 kilograms.
The body is scaleless and covered in silvery guanine, with a dorsal fin of about 400 rays running from above the small eyes to the tail end; the first rays form a red crest. There is no anal fin and no swim bladder, and the pelvic fin is a single, extremely long, ornamented ray (Florida Museum; FishBase).
Quick facts
- Group
- Fish
- Length
- 3 to 8 m
- Weight
- up to 272 kg
The deep, open ocean
Oarfish live in the open ocean, far from land.
They swim deep down. Sometimes one washes up on a beach, and that is how people see them.
Giant oarfish live in oceans all around the world, but only away from the polar seas. They live in the open ocean, from near the surface down to about 1,000 meters, though usually no deeper than about 200 meters.
Oarfish are very rarely seen alive. Most people who see one find it washed up on a beach, often after a storm, or spot it near the surface when it is sick or injured.
The IUCN describes a circumglobal range at 15 to 1,000 meters in the epipelagic and mesopelagic zones, from New England to the Caribbean and Gulf of Mexico, the Mediterranean, Argentina, and the South Atlantic, Indian and Pacific Oceans. FishBase notes a cool-water, anti-tropical pattern at latitudes beyond about 15 degrees, and the Florida Museum says it is thought to be found everywhere except the polar seas, typically above 200 meters.
It is rarely recorded. Live encounters are rare; individuals are sighted near the surface or stranded, usually after storms (IUCN), and the Florida Museum notes that the first live oarfish filmed by the US Navy was in 2001.
Its habitat
Where can you find this animal?
- Lives here naturally · Countries and seas named by a scientific source
- Sightings recorded · Records of wild sightings (GBIF)
Lives here naturally · Countries and seas named by a scientific source
The open ocean worldwide except the polar seas, from about 15 to 1,000 meters deep, including the Mediterranean. Shading is by whole ocean; the fish is rarely recorded anywhere, and most records come from strandings.
Places: Atlantic Ocean, Indian Ocean and Pacific Ocean.
Source: iucn-red-list · checked October 2026
Sightings recorded · Records of wild sightings (GBIF)
Counts of GBIF records of wild observations (human and machine) and preserved specimens. Records include introduced populations, vagrants, escaped or released animals and misidentifications, so a country with records is not necessarily part of the native range.
Wild sightings have been recorded in Australia, United States, New Zealand, South Africa, Mexico, Norway, Belize, France and 20 more places.
Source: gbif · checked October 2026
Range maps show where scientists say an animal lives, often country by country. An animal may live in only part of a country shown, and sightings records can include animals that wandered far from home.
Sipping krill
Oarfish eat tiny sea animals called krill.
They have no teeth. They suck in water and catch the krill with combs in their mouth.
Oarfish mainly eat krill, tiny shrimp-like animals that drift in the ocean. They have no teeth. Instead, they push out their mouth to suck in water full of krill, and long, bristly combs in the throat, called gill rakers, hold the krill in.
One oarfish caught off California had about 10,000 krill in its stomach!
The Australian Museum notes that all verified stomach contents have been krill (euphausiids), and that reports of fish and other prey are unvalidated; the IUCN and FishBase also list small fishes, squids and planktonic crustaceans. Toothless, protrusible jaws suck krill-laden water into the mouth, where long, spiny gill rakers retain it (FishBase).
The Florida Museum records one Californian specimen with about 10,000 krill. FishBase notes that the vertical, head-up posture may help the fish spot prey silhouetted against the light from above, a hypothesis rather than an established fact.
Did you know?
An oarfish can lose the end of its body and keep living.
A big oarfish can shed the end of its long body, and it still keeps living. The lost part never grows back.
Serial autotomy of the posterior body occurs, apparently several times in a lifetime, without damaging vital organs; lost parts never regenerate (FishBase).
A fin that ripples
The oarfish swims by waving the long fin on its back.
Its body stays straight. Long, thin red fins hang down from under its head.
An oarfish swims in a special way. Its body stays straight and stiff, and the long fin on its back ripples in waves to push it along. It often hangs upright in the water, head up.
The name oarfish may come from its flat, oar-like body, or from the long fins under its head. People once thought it 'rowed' with those fins, but scientists now think they may be used for sensing taste instead.
Swimming is amiiform: the body stays straight while the dorsal fin undulates (Florida Museum). Underwater footage shows oarfish swimming slowly and vertically, head up, with a stiff body and photophores on the appendages (FishBase).
Large oarfish usually lack a tail fin. FishBase describes autotomy: the fish can shed the rear part of its body, sometimes several times in its life, without damaging vital organs, and the lost part never regrows; individuals over about 1.5 meters have shortened bodies ending in a healed stump. The Australian Museum notes that the long pelvic fins, once thought to row the fish along, are now believed to be used for taste.
Floating red eggs
Oarfish mothers lay lots of eggs.
The eggs are big and red, and they float near the top of the sea. Tiny oarfish hatch and grow up in the ocean.
Scientists know very little about how oarfish breed. Off Mexico, they have been seen spawning between July and December. The eggs are large, about 2 to 4 millimeters across, red, and float near the surface. They may take up to three weeks to hatch.
A single female can carry a huge number of eggs: one female caught off Florida held about 139,000. Baby oarfish look like tiny versions of the adults and eat plankton as they grow.
Reproduction is poorly known (IUCN). Spawning occurs between July and December, and larvae are found near the surface (FishBase). Eggs are 2 to 4 millimeters, red, free-floating and contain oil droplets; incubation is thought to take up to three weeks (Florida Museum). A Florida female contained about 139,043 eggs averaging 2.57 millimeters (IUCN).
FishBase lists probable spawning areas off western Florida and the northern coast of America, near the Strait of Messina in the Mediterranean, at New Zealand's Chatham Rise, and off southern Western Australia. Larvae resemble miniature adults and feed on plankton (Florida Museum).
A solitary drifter
Oarfish usually live alone.
They hang straight up and down in the water, very still, with their head at the top.
Oarfish are believed to live alone, except when spawning. Sometimes two are seen together, but never big groups.
They often hang upright in the water, head up, with the crest on their head pointing up and their long fins spread out. The Florida Museum says scientists believe this upright swimming may be how oarfish search for food.
The species is thought to be solitary outside spawning (Florida Museum); FishBase notes occasional pairs but no records of groups larger than three or of schooling. The vertical, head-up stance, with dorsal crest rays raised and pelvic rays spread, is commonly observed (FishBase).
The Florida Museum notes that vertical swimming is believed to be a way of searching for prey, and FishBase cites a hypothesis that the stance helps the fish spot prey silhouetted against the skylight. Strandings, FishBase notes, may cluster in certain areas and seasons.
Did you know?
A live oarfish was not filmed until 2001.
Live oarfish are so rarely seen that the first one filmed by the US Navy was in 2001.
The Florida Museum notes that a live oarfish was first captured on film by the US Navy in 2001.
Rare to see, not in danger
Oarfish are not in danger.
They live far out in the deep sea, where few people go. People do not catch them to eat.
The IUCN lists the giant oarfish as Least Concern. It lives across a huge area of ocean, and no major threats are known.
People rarely catch oarfish, and their soft, jelly-like meat is not good to eat. Because they live so deep and are so rarely seen, there is still a lot that scientists do not know about them.
The IUCN assessed Regalecus glesne as Least Concern (assessed May 2013, published 2015; annotated as needing an update), with an unknown population trend and no known major threats. It is not used commercially, and the flesh is considered unpalatable; FishBase notes it is occasionally caught with encircling nets and sold fresh in some places.
There are no species-specific conservation measures. Its biology, including growth, lifespan and reproduction, remains poorly known because live encounters are so rare; regional assessments also exist for Europe, the Gulf of Mexico and the Mediterranean.
IUCN Red List
How is the giant oarfish doing in the wild?
- Least Concern (this animal)
- Near Threatened
- Vulnerable
- Endangered
- Critically Endangered
- Extinct in the Wild
- Extinct
Least Concern
Not at risk of disappearing from the wild right now.
See the IUCN Red List assessment · The IUCN Red List of Threatened Species 2022.2
Amazing facts
-
The oarfish is the longest bony fish.
The giant oarfish is the longest bony fish: the longest reliably measured was about 8 meters.
It is recognized as the longest bony fish, reliably documented to 8 meters (Australian Museum).
-
Oarfish have no teeth.
Oarfish have no teeth. Bristly combs in their throat catch the krill they suck in.
Toothless, protrusible jaws and long, spiny gill rakers retain krill (FishBase).
-
A live oarfish was not filmed until 2001.
Live oarfish are so rarely seen that the first one filmed by the US Navy was in 2001.
The Florida Museum notes that a live oarfish was first captured on film by the US Navy in 2001.
-
An oarfish can lose the end of its body and keep living.
A big oarfish can shed the end of its long body, and it still keeps living. The lost part never grows back.
Serial autotomy of the posterior body occurs, apparently several times in a lifetime, without damaging vital organs; lost parts never regenerate (FishBase).
Words to know
- krill
- tiny shrimp-like animals that drift in the ocean
- dorsal fin
- a fin on the back of a fish
- gill rakers
- comb-like parts in a fish's throat that catch food from the water
- stranded
- stuck on a beach or in shallow water, away from where the animal lives
- open ocean
- the part of the sea far from coasts
- plankton
- tiny living things that drift in the water
Discovery challenge
-
What shape is an oarfish?
What is the giant oarfish's body shaped like?
Which describes the body form of Regalecus glesne?
- Long like a ribbon
- Round like a ball
- Flat like a pancake
Show the answer
Long like a ribbon
It is very long and thin, like a ribbon.
It has a long, flat, ribbon-shaped silver body.
Highly elongate and compressed, ribbon-like, with a full-length dorsal fin.
-
What does an oarfish eat?
What is the giant oarfish's main food?
What prey dominates verified oarfish stomach contents?
- Krill
- Seaweed
- Big sharks
Show the answer
Krill
It eats tiny animals called krill.
It mainly eats krill, which it sucks in and catches with comb-like gill rakers.
Krill (euphausiids); other prey reports are unvalidated (Australian Museum).
-
How does an oarfish swim?
How does a giant oarfish swim?
What mode of locomotion does the oarfish use?
- It ripples the long fin on its back
- It flaps its tail fast
- It walks on its fins
Show the answer
It ripples the long fin on its back
It waves the long fin on its back, and its body stays straight.
Its body stays stiff while the long back fin ripples in waves.
Amiiform swimming: undulation of the long dorsal fin with a straight body.
-
Where do people usually see oarfish?
Why have so few people seen a live oarfish?
Why are most oarfish records from strandings?
- They live deep in the open ocean
- They hide in rivers
- They only come out in winter
Show the answer
They live deep in the open ocean
They live deep in the sea, so people mostly see ones that wash up on beaches.
They live far out and deep in the ocean, so people usually only see oarfish washed up on beaches.
It is an epi-mesopelagic, rarely recorded species; most individuals are seen stranded or near the surface after storms.
Places where you might see it
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Watch
Country
Australia
Australia is a country and the smallest continent, surrounded by ocean in the Southern Hemisphere. Much of its middle is dry and flat, most people live near the coast, and its animals include kangaroos, koalas and the platypus, a mammal that lays eggs.
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Watch
Country
New Zealand
New Zealand, also called Aotearoa, is an island country in the South Pacific. Its two main islands have snowy mountains, glaciers, volcanoes and deep fiords, and about 5.36 million people lived there in 2026.
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For parents & teachers
What children will learn
- Describe the giant oarfish's body and how it swims by rippling its dorsal fin.
- Explain how the oarfish feeds on krill without teeth.
- Understand why deep-sea animals are hard to study and why most photos show stranded specimens.
Recommended ages: 3 to 17 · About 10 minutes
Talk about it
- Why do you think scientists still know so little about oarfish?
- How might hanging head-up in the water help a fish find food?
- What tools could scientists use to study animals that live deep in the ocean?
Try at home or in class
- Measure 8 meters with a long string or tape in a hallway or yard: that is the longest well-documented oarfish.
- Ripple a long ribbon along a table edge to see how waves moving along a fin could push a fish forward.
Key vocabulary: krill, dorsal fin, gill rakers, stranded, open ocean, plankton
Where these facts come from
- The IUCN Red List of Threatened Species , International Union for Conservation of Nature (IUCN terms of use (no redistribution of Red List data or range maps))
- GBIF Backbone Taxonomy and GBIF Occurrence Search , Global Biodiversity Information Facility (CC0 1.0 (backbone); occurrence counts are facts derived from records under CC0, CC BY and CC BY-NC)
- Regalecus glesne (Oarfish), 2015 global assessment , IUCN Red List of Threatened Species
- Oarfish, Regalecus glesne , Australian Museum
- Oarfish (Regalecus glesne) , Florida Museum of Natural History
- Regalecus glesne, King of herrings: species summary , FishBase
- Wikidata , Wikimedia Foundation (CC0 1.0)
- Wikimedia Commons , Wikimedia Foundation (Per file: Public domain, CC0, CC BY or CC BY-SA only (credited on each page))
Checked, not yet human-reviewed. Last updated October 27, 2026. Spotted a mistake? Tell us.