Regalecus glesne

Last updated: October 6, 2022
Verified by: AZ Animals Staff
© Dotted Yeti/Shutterstock.com

The Giant oarfish (Regalecus glesne) holds the Guinness Book of World Records for the longest bony fish in the world.


Oarfish Scientific Classification

Scientific Name
Regalecus glesne

Read our Complete Guide to Classification of Animals.

Oarfish Conservation Status

Oarfish Locations

Oarfish Locations

Oarfish Facts

Krill, shrimp, plankton, squid, and small fish
Main Prey
Group Behavior
  • Solitary
Fun Fact
The Giant oarfish (Regalecus glesne) holds the Guinness Book of World Records for the longest bony fish in the world.
Most Distinctive Feature
Elongated body in the shape of a ribbon
Other Name(s)
Ribbon Fish, Streamer Fish, King of Herrings, Pacific Oarfish
Deep Ocean
Sharks and killer whales
Favorite Food
Common Name
Number Of Species

Oarfish Physical Characteristics

  • Silver
Skin Type

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The Giant oarfish (Regalecus glesne) holds the Guinness Book of World Records for the longest bony fish in the world. They are found in the depths of the Mediterranean sea and the eastern Atlantic Ocean and have a ribbon-like appearance.

Oarfish are members of the Refalecidae family and are also known as the King of Herrings because their dorsal fin looks like a crown. Their dorsal fins run down the entire length of their gigantic bodies, with a tiny spine located above 400 individual fin rays.

The oarfish’s pelvic fins are elongated and similar in color to their bodies. The King of Herrings is a rare species because they primarily inhabit deep sea waters.

They move their pelvic fins in a circular motion, very similar to an oar, hence the name. These unique fish use their dorsal fins to help them swim and swim in a vertical position.

Three Amazing Oarfish Facts!

  • The oarfish resembles a giant snake or dragon because of their elongated bodies. In addition, they are smooth and lack scales, with tubercules and a guanine coat topped with omate and a red dorsal fin.
  • Their flesh is sought after by fishermen because it is so rare. The texture is sticky and jelly-like
  • There is a superstitious folklore in Japan that when an oarfish washes up dead on the shore, it’s considered a sign of impending doom like a Tsunami or Earthquake. For example, 20 dead oarfish washed up on shore just before Japan’s 2011 tsunami.

Oarfish Scientific Name

The oarfish’s scientific name is Regalecus glesne and consists of three species in two genera. One of these species is the Giant Oarfish.

Giant Oarfish

Giant oarfish is a species of bony fish that got its name from the shapes of its pelvic fins that it rotates like an oar. They are often compared to monsters because of their elongated bodies and massive size. The giant oarfish can grow to lengths of 56 feet and can weigh a whopping 600 pounds!

They have flat, long tapering bodies that are reflective silver in color, and a dorsal fin that runs down their entire body, which they use to help them swim.

These giants are deep sea fish that occur in the Gulf of Mexico. They go by many names, which include:

  • Ribbon Fish
  • Streamer Fish
  • King of Herrings
  • Pacific Oarfish

In addition, many people refer to them as sea serpents because they look so similar when they appear close to the surface.

The fin rays near their heads lengthen to form a distinctive bright red crest that has evolved over many years to act as a defense mechanism against predators.

An interesting fact about oarfish is that most of their organs are situated close to the head, so even if their elongated tails are cut off, they can still survive.

Giant oarfish live in the deepest depths of the ocean, but sometimes when they die, they wash up on shore, especially after a brutal storm.


Oarfish belong to the order Lampriformes, and while families of this order don’t look alike, they all share the following characteristics that distinguish them from other orders of ray-finned fishes:

  • Compressed body
  • Ribbon-like appearance
  • No true spines on fins; rays only
  • Thoracic pelvic fins


The oarfish are members of the Regalecidae family, consisting of small oceanic fish with elongated, ribbon-shaped bodies. In addition, their upper dorsal fin rays are longer than the others and contort into a crown or crest above the head. The pelvic fins only have a single ray trailing below the body.

There are only three species of oarfish, and they include:

  • The Giant Oarfish
  • The streamer fish
  • Regalecus russeii

Oarfish Appearance

The oarfish’s most distinctive feature is its elongated body. However, they are rarely seen because they inhabit the deepest depths of the ocean.

Oarfish have a reflective silvery color, and their skin is rubbery and smooth (they have no scales). Their bodies are covered in wavy markings and coated in guanine, which is one of the building blocks of DNA and RNA.

Unlike most fish, oarfish don’t have anal fins; instead, they have a long dorsal fin, which runs down their entire body. Their pectoral fins are located on the lower part of their bodies.

An interesting fact about the oarfish is that their mouths are capable of extending or protruding. And while the sea serpent is not real, many people believe their myth originated with the giant oarfish because of their massive size and snake-like appearance.

The giant oarfish holds the record for the longest-living bony fish in the world. They can grow up to 56 feet long and weigh up to 600 pounds!

Oarfish Behavior

There is very little research about the oarfish’s behavior. In fact, marine biologists did not record this species in their natural habitat until 2010.

They use their elongated dorsal fin to help them swim in search of prey. But their swimming style is very unusual. They swim horizontally with their bodies in a column-like position, with their heads facing upward and tails downward.

Oarfish Habitat

Oarfish are native to the western Indian Ocean, southwest Pacific, northeast Atlantic, western central Atlantic, eastern central Pacific, northwest Atlantic, Mediterranean, and the Black Sea, western central Pacific, eastern central Atlantic, southeast Atlantic, southwest Atlantic, and the east Indian Ocean.

The giant oarfish inhabit pelagic waters (deep waters) or open oceans. Which means they do not occur close to the coast. They are mainly found in the mesopelagic and epipelagic zones of the deep sea.

These serpent-like fish live in habitats as far down as 3000 feet, and the shallowest waters they inhabit are around 600 feet below the surface.

Oarfish Diet

Oarfish are carnivores, but despite their massive size, their prey is primarily small marine creatures. The main component of their diet is Krill; however, they also feed on:

Unfortunately, because researchers have only observed a few live specimens, there is very little information about their hunting behavior.

However, researchers have observed the oarfish eating by suctioning prey like plankton blooms while in the water.

Oarfish Predators and Threats

While not much is known about this pelagic fish, they likely fall prey to large open-ocean carnivores like Great White Sharks and Orcas.

These massive creatures have no known significant threats. Most of them die from natural causes or predation, and their bodies often float to the surface or wash up on beaches.

Giant oarfish are sometimes caught in nets meant for other species;  however, these are very rare occurrences, and it does not affect their overall population numbers. In fact, the IUCN has listed them as Least Concern on their Redlist.

Oarfish Reproduction, Babies, and Lifespan

Oarfish are oviparous and reproduce by releasing their eggs and sperm into the ocean. Spawning takes place during the months of July and December once the temperatures begin to rise.

The eggs lay on the surface until they hatch and develop into larvae within 3 weeks. Juveniles have distinctive long rays on the pelvic and dorsal fins. Once they grow up, they live a solitary life.


Unfortunately, there is no available information about the oarfishes’ lifespan.

 Oarfish Population

There are no definitive estimates of the population size of this fish. They have three species with two genera, and sightings of any of these three species are very rare.

Importance to Humans

These massive fishes are not of commercial value due to their location deep within the ocean and their poor quality of meat, which is a gelatinous texture, and considered inedible.

However, some consider them gamefish, and they catch them with encircling nets where they market them fresh in some local areas.

But, in general, they are rarely observed by humans, only when swimming on the surface or washed up dead on the coasts. The first time one was very caught on film was in 2001 by the US Navy.

Fish Species Similar to the Oarfish

Very few species are similar to the oarfish because they are incredibly unique. However, 3 species belong to the same order, Lampriformes, and share similar characteristics with the King of Herrings. They include:


Crestfish form part of a small family called Lophotidae and are often referred to as unicornfish. They are bony fish that inhabit the deep waters of the ocean.

Crestfish have box-like heads, ribbon-shaped silvery bodies, crimson fins, and protruding foreheads. Similar to the oarfish, crestfish have a prominent dorsal fin that extends the length of their bodies, and their upper rays form a crown or crest above their heads, hence the name crestfish.

In addition, they also have a short anal fin and no pelvic fin. However, what sets them apart from oarfish is their ink sacs that open into the cloaca and release a black cloud of smoke. This is used to defend themselves, just like squids.

Some species of crestfish, like the Lophotus capellei, have no scales. However, other species like the L. lacepede have small cycloid scales that easily rub off if touched.


Opahs go by many names, including:

  • Sunfish
  • Moonfish
  • Redfin ocean pans
  • Kingfish
  • Jerusalem haddock

They are lamprey fish that are large in stature, deep-bodied and colorful deep-water-dwelling creatures. An interesting fact about ophas is that they are warm-blooded, which was only recently discovered.

They maintain a core body temperature of 41ᵒF, which is hotter than the water surrounding them. This is a very unusual feature as most fish species are cold-blooded or can only warm specific parts of their bodies.

There are two living species of opah, Lampris immaculatus, and Lampris guttatus. Opahs are disc-shaped, compressed, deeply keeled, and colorful. They are multicolored with rosy to deep reddish-orange bellies, and their flanks are covered in white spots. In addition, their median and paired fins are bright orange.

Opahs have large, distinctive eyes with golden rings around them. They are covered in tiny cycloid scales, and their bodies are coated in silvery iridescent guanine.

Opah’s shape resembles the butterfish, with notched forked caudal fins and a curved pectoral fin. In addition, they have curved pectoral fins with 14 to 17 rays. However, unlike other fish, their rays are inserted vertically, not horizontally. They have a single curved dorsal fin, and their anal fin is elongated and high.


Ribbonfish’s scientific name is Desmodema polystictum, and they are members of the trachipteridae family, which belongs to the genus Trachipterus. These fish are native to the Atlantic, Indian, Pacific, and Mediterranean Oceans.

They derive their name from their ribbon-like appearance. For example, when swimming, they resemble a long piece of ribbon floating across the water.

There are different varieties of the species that include:

  • Cutlassfish
  • Blue ribbon fish
  • Polka dot ribbon fish
  • Ribbon sawtail fish
  • Giant ribbon fish
  • Ribbon dragon fish
  • Florida ribbonfish

Ribbonfish are often used as bait for the purpose of catching several larger fish. Unfortunately, they inhabit the deep waters of the ocean, so they are a rare sight to see. In fact, people rarely see them alive in their natural habitat.

Researchers usually have to wait until they are captured or washed up onshore to study them. However, they are a pelagic species, which means they do not live on the ocean floor, but can still inhabit depths of around 3000 feet.

Ribbonfish have elongated bodies and can grow up to 6.5 feet long, which makes them easily distinguishable from other fish species. In addition, they have caudal fins that point upwards, large bright-colored dorsal fins that run the length of their bodies, and no anal fins.

There are 6 subspecies of the genus Trachipterus, and they all have laterally compressed, ribbon-like bodies and the exact characteristics of deep-sea dwelling animals. Ribbonfish is a delicacy in many countries and possesses abundant health benefits.

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About the Author

Chanel Coetzee is a writer at A-Z Animals, primarily focusing on big cats, dogs, and travel. Chanel has been writing and researching about animals for over 10 years. She has also worked closely with big cats like lions, cheetahs, leopards, and tigers at a rescue and rehabilitation center in South Africa since 2009. As a resident of Cape Town, South Africa, Chanel enjoys beach walks with her Stafford bull terrier and traveling off the beaten path.

Oarfish FAQs (Frequently Asked Questions) 

What is the largest giant oarfish?

The maximum reported length of the oarfish is 36 feet.

Are giant oarfish edible?

No, their flesh is very gelatinous and inedible.

How deep do giant oarfish live?

These serpent-like fish live in habitats as far down as 3000 feet, and the shallowest waters they inhabit are around 600 feet below the surface.

What do giant oarfish eat?

The main component of their diet is Krill; however, they also feed on shrimp, plankton, squid, and small fish.

Thank you for reading! Have some feedback for us? Contact the AZ Animals editorial team.


  1. Oh Fact, Available here: https://ohfact.com/oarfish-facts/
  2. Kidadl, Available here: https://kidadl.com/facts/animals/oarfish-facts
  3. Wikipedia, Available here: https://en.wikipedia.org/wiki/Oarfish
  4. Animal Spot, Available here: https://www.animalspot.net/giant-oarfish.html
  5. Animals.net, Available here: https://animals.net/oarfish/#:~:text=Behavior%20of%20the%20Oarfish&text=The%20species%20uses%20its%20elongated,downward%20and%20their%20head%20upward.

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