All About Oarfish: Guardians of The Deep

Leave a comment / / Updated on: 11th November 2023

Scientific nameRegalecus glesneWeight270 kilograms (600 pounds)
Pronunciationawr-fishLength11 meters and above (433.1 inches and above)
ClassificationActinopterygii,‭ Lampriformes,‭ & RegalecidaeLocationWorldwide, except Antarctica

The Oarfish

Gage Beasley's Oarfish Stuffed Plush Toy
Gage Beasley’s Oarfish Stuffed Plush Toy

Considering how vast the Earth’s waters are, it is only right to say that fish are undeniably one of the most populous species on Earth, boasting a remarkable diversity that spans oceans, rivers, lakes, and ponds across the globe. 

The number of fish species is staggering, with thousands of distinct varieties identified and many more yet to be discovered. 

This vast array of species contributes significantly to Earth’s overall biodiversity. 

From the smallest reef-dwelling species to the largest aquatic giants, they form an intricate web of life that supports countless other marine organisms. 

Their presence in such vast numbers helps maintain the delicate balance of aquatic ecosystems. 

These fish play crucial roles in nutrient cycling, food chains, and even the livelihoods of human communities through fishing and aquaculture. 

Fishing has been a source of sustenance and livelihood for countless communities throughout history. 

A Giant Oarfish on a black background
A Giant Oarfish on a black background / dottedhippo via iStock

While many species are considered popular, others are not, including the oarfish.

Oarfish are quite rare and elusive sea creatures that inhabit the mesopelagic and bathypelagic zones of the ocean, typically at depths ranging from 656 feet to over 9,800 feet. 

Due to their remote and deep-sea habitat, humans rarely encounter them. 

Instead, most encounters with oarfish occur when they wash ashore, usually due to natural events such as storms or currents. 

These strandings are relatively rare and often attract scientific attention due to the opportunity they provide to study these mysterious creatures. 

Over the years, experts have studied this species and collected as much information regarding them as possible, some of which will be brought to light in the subsequent portions of this article.

Gage Beasley's In-Demand Plush Toys
Gage Beasley’s In-Demand Plush Toys

Taxonomy and Classification

Illustration of Oarfish swimming in undulating motion | Dorling Kindersley via Getty Images

Oarfish are chordates, possessing a notochord, a dorsal nerve cord, and pharyngeal slits at some point during their development. 

As vertebrates, oarfish have a well-developed vertebral column or spine. 

These fish belong to the Actinopterygii class, including ray-finned fishes characterized by bony rays supporting their fins. 

The oarfish belongs to the family Regalecidae within the order Lampriformes. 

These elongated, ribbon-like fish are further divided into two genera: Regalecus and Agrostichthys.

The genus Regalecus includes the giant oarfish (Regalecus glesne), the largest of its kind. 

This species is recognized for its impressive size, often reaching lengths up to 36 feet. 

Oarfish with its distinctive red fins
Oarfish with its distinctive red fins / Hein Nouwens via iStock

Its slender, ribbon-like body is silver, with distinctive red fins along its dorsal ridge. 

The giant oarfish is usually found in deep ocean waters, often between 200 and 1,000 meters below the surface.

On the other hand, the Agrostichthys includes the smaller oarfish species, such as the streamer oarfish (Agrostichthys parkeri). 

These species are generally shorter than their giant oarfish relatives, ranging from 6-15 feet. 

They share similar ribbon-like bodies and are often characterized by colorful patterns and luminescent organs, which are believed to be used for communication and camouflage. 

While much remains to be discovered about these deep-sea giants, their classification serves as a foundation for further research and a deeper understanding of the mysteries of the ocean’s depths.

Physical Characteristics

United States Navy SEALS holding a 23-foot giant oarfish, washed up on the shore near San Diego, California
United States Navy SEALS holding a 23-foot giant oarfish, washed up on the shore near San Diego, California / Leo Smith via Wikipedia Public Domain

One of the most striking physical features of the oarfish is its exceptional length. 

Oarfish grow to astonishing lengths, with some reaching up to 36 feet or more. 

This makes them the longest bony fish in the world. 

Their slender, ribbon-like bodies make them particularly unique in the realm of ocean creatures. 

The body of the oarfish is covered in silvery scales that shimmer and reflect the faint light penetrating the deep-sea environment. 

These scales provide camouflage in their habitat, helping them blend in with the surrounding waters. 

Running the entire length of their bodies is a prominent dorsal fin. 

An artistic depiction of the oarfish, showcasing its distinctive dorsal fin
An artistic depiction of the oarfish, showcasing its distinctive dorsal fin / Rvalette via Wikimedia Commons CC A-SA 3.0

This dorsal fin is unique among fish species and serves multiple purposes. 

It aids in propulsion, allowing the oarfish to move efficiently through the water despite its elongated shape. 

Additionally, the fin can be raised and lowered, enabling the oarfish to maintain stability in the turbulent waters of the deep sea. 

The first 10 to 13 of the roughly 400 dorsal fin rays are lengthened to variable degrees, generating a trailing crest with reddish patches and skin flaps at the ray tips.

The head of the oarfish is small in comparison to its body, featuring a small mouth. 

Like other members of its group, the oarfish has an invisible oblique mouth that is small yet very protruding. 

The skin is covered in easily abraded, silvery ganoine, and the body is scaleless. 

Oarfish are believed to be weak swimmers, relying mostly on undulating their dorsal fin to move
Oarfish are believed to be weak swimmers, relying mostly on undulating their dorsal fin to move / dottedhippo via iStock

The color of oarfish can also vary; the flanks are frequently covered in erratic bluish-to-blackish streaks, black spots, and squiggles.

Following death, these markings quickly disappear. 

It is likely that in the deep sea, these marks are bioluminescent. 

They have photophores along their bodies that produce light, which may serve various purposes, including communication, attracting prey, or potentially deterring predators in the dark depths. 

This coloration is also thought to be another adaptation to their deep-sea environment, where red light is absorbed, making them less visible to potential predators and prey.

Habitat and Distribution

Oarfish are known for their deep-sea lifestyle. 

Oarfish are believed to live in the epipelagic to mesopelagic ocean layers between 660 and 3,300 feet below the surface and are infrequently observed there. 

A handful that are barely alive have been discovered, but typically, if one floats to the surface, it dies from depressurization. 

There are either little or no currents where the oarfish reside. 

They cannot survive in shallower, turbulent water due to their limited muscle growth. 

Oarfish are not limited to a specific region of the ocean. 

They have been recorded in various parts of the world, including the Atlantic, Pacific, and Indian Oceans. 

Oarfish sighting in Los Cabos, Baja California Sur, Mexico
Oarfish sighting in Los Cabos, Baja California Sur, Mexico / Katia Cao via Wikimedia Commons CCA 3.0

Some notable locations where oarfish sightings have occurred include the waters of Japan, California, New Zealand, and Mexico. 

Despite their global distribution, oarfish are rarely seen by humans. 

Their elusiveness has contributed to the many myths and legends surrounding them. 

When oarfish appear near the ocean’s surface, it is often after storms or other unusual events, further adding to their mystique.

Behavior and Social Structure

Oarfish are generally solitary, with sightings of multiple individuals being exceptionally rare. 

This solitary behavior adds to their elusive reputation. 

Illustration of an Oarfish
Illustration of an Oarfish / image via Wikimedia Commons Public Domain

Oarfish are known for their vertical migrations within the water column. 

They often move closer to the surface at night and descend to deeper depths during the day. 

This behavior is believed to be related to their feeding patterns and avoidance of predators. 

This fish has also been seen swimming in an amiiform manner, which involves rhythmically waving the dorsal fin while maintaining a straight body. 

As previously mentioned, oarfish are predominantly solitary creatures. 

However, there is limited scientific data on their social behavior. 

While they may encounter each other in their deep-sea habitats, they do not form the large, structured social groups seen in some other fish species.

Diet and Feeding

Creative illustration of an Oarfish
Creative illustration of an Oarfish / Elena Hartley via Getty Images

Oarfish are deep-sea dwellers primarily found in tropical and temperate waters worldwide. 

Due to their elusive nature and preference for deeper waters, studying their diet has proven challenging. 

While there is limited direct observation of oarfish feeding in their natural habitat, scientists have made educated hypotheses about their diet based on their anatomy and the contents of their stomachs when caught. 

Oarfish are considered opportunistic predators, which means they likely feed on a variety of small prey items available to them in their deep-sea environment. 

Oarfish are believed to feed primarily on zooplankton, tiny marine organisms that drift with ocean currents. 

When the opportunity arises, they consume small fish and cephalopods (like squid and small octopuses). 

Their long, ribbon-like bodies and extended dorsal fin rays may be effective tools for corralling and capturing such small prey. 

The oarfish is known as the world's longest bony fish
The oarfish is known as the world’s longest bony fish / Universal History Archive via Getty Images

Oarfish have been observed by scientists sucking plankton blooms and other prey while submerged in the water. 

Oarfish may also scavenge on carrion that sinks from the surface to the deep sea. 

Their ability to reach great depths allows them to access food sources that are otherwise unavailable to most marine creatures.

Reproduction and Life Cycle

Scientists know relatively little about the real breeding behaviors of these fish, much like the topic of behavior.  

What we do know is that oarfish are oviparous, meaning they lay eggs. 

A single female can lay hundreds of thousands of eggs. 

It releases its eggs into the water column, where they float unhindered. 

Close-up view of a young oarfish
Close-up view of a young oarfish / d3_plus D. Naruse via Getty Images

These eggs hatch into larvae and then journey into the open ocean. 

After hatching, the larvae of oarfish undergo a pelagic phase, drifting in the open ocean currents. 

During this time, they feed on plankton and other small organisms. 

They undergo a series of transformations as they grow, eventually developing into the impressive adults we recognize. 

The larvae’s long dorsal and pelvic fins and extendable jaws distinguish them from the adults. 

Juveniles and larvae have been seen wandering close to the surface. 

On the other hand, adult oarfish are hardly spotted at the surface when healthy or injured. 

The likelihood is that when fish get older, they migrate deeper.

Ecological Role and Interactions

Larval oarfish two days after hatching
Larval oarfish two days after hatching / Oka, 2020 via Wikimedia Commons CCA 4.0

One of the key ecological roles of oarfish lies in their potential as indicators of ocean health

Oarfish are highly sensitive to changes in environmental conditions, including temperature, water quality, and food availability. 

Their presence or absence in specific areas can offer valuable insights into deep-sea ecosystems’ overall health and stability. 

Scientists have observed that fluctuations in oarfish populations often coincide with shifts in oceanic conditions, making them valuable bioindicators. 

Oarfish feed on various prey, including smaller fish and invertebrates. 

As predators in the deep-sea food web, they play a role in regulating the populations of their prey species. 

Additionally, when oarfish die and sink to the ocean floor, they become part of a process known as marine snow. 

Marine snow is a shower of organic material falling from upper waters to the deep ocean
Marine snow is a shower of organic material falling from upper waters to the deep ocean / OAA National Ocean Service via Wikipedia Public Domain

Their carcasses provide nutrients to deep-sea scavengers and bacteria, contributing to nutrient cycling in the deep ocean. 

Recycling organic matter is essential for maintaining the health and productivity of deep-sea ecosystems. 

While oarfish are formidable predators in their own right, they are not immune to predation themselves. 

Larger predators, such as sharks and some species of cetaceans, have been known to feed on oarfish. 

This interaction highlights the interconnectedness of marine ecosystems and underscores the importance of oarfish in the deep-sea food web. 

Oarfish serve as a link between lower trophic levels and apex predators in these habitats.

Conservation Status and Threats

Giant oarfish at the Aqua World Ibaraki Prefectural Oarai Aquarium
Giant oarfish at the Aqua World Ibaraki Prefectural Oarai Aquarium / Ryokou Man via Wikimedia Commons Public Domain

The International Union for Conservation of Nature (IUCN) does not officially classify the conservation status of oarfish. 

This absence of an official status might lead one to believe that oarfish populations are thriving; however, this is only sometimes true. 

The lack of data and research on oarfish populations and their behaviors has made it difficult to assess their conservation status accurately. 

Oarfish are often unintentionally caught in fishing nets meant for other species. 

Their fragile bodies are susceptible to damage during capture, making them vulnerable to injury or death. 

Pollution in the form of plastics, chemicals, and other contaminants also poses a significant threat to oarfish and other marine life. 

Activities such as deep-sea mining and bottom trawling can cause severe damage to the fragile habitats where oarfish live. 

Deep sea mining schematic with independant platform
Deep sea mining schematic with independant platform / G.Mannaerts via Wikimedia Commons CC A-SA 4.0

These destructive practices can lead to the loss of critical feeding and breeding areas. 

Stricter regulations on waste disposal and efforts to reduce plastic pollution can help safeguard oarfish and other marine life. 

Also, establishing Marine Protected Areas can help protect critical deep-sea habitats where oarfish are likely to reside. 

These protected areas can provide refuge from fishing and habitat destruction.

Unique Adaptations and Survival Strategies

One of the most distinctive features of the oarfish is its incredibly long body, which can reach lengths of up to 36 feet or more. 

This elongated shape allows them to navigate the deep ocean with ease. 

Oarfish head / Parker,1890 via Wikimedia Commons Public Domain

Their slender bodies reduce drag, making swimming in the open water more energy-efficient. 

Oarfish are adorned with striking, silver-colored scales that reflect and refract light, creating an otherworldly appearance. 

These scales may serve multiple purposes, including camouflage and attracting prey. 

Bioluminescence plays a critical role in survival in the depths where sunlight is scarce. 

Their ability to make vertical migrations allows them to exploit different food sources and avoid potential predators. 

Despite their distinctive appearance, oarfish still need to be discovered. 

They are rarely encountered alive and are more commonly found washed ashore, often in a distressed or dying state.

Dead Oarfish that washed ashore on a beach in Mexico
Dead Oarfish that washed ashore on a beach in Mexico / Eric Broder Van Dyke via iStock

Scientists are still unraveling the mysteries of their behavior, migration patterns, and reproductive strategies.

Cultural Significance and Human Interactions

Oarfish have often been associated with myths and legends in various cultures. 

In Japan, they are known as Ryugu no tsukai or “Messengers from the Sea God’s Palace.” 

According to Japanese folklore, oarfish sightings are considered omens of impending earthquakes or tsunamis

Similarly, in other parts of the world, the appearance of an oarfish has been linked to superstitions and mysterious occurrences. 

The striking appearance of the oarfish, with its long, silvery body and vibrant red dorsal fin, has inspired artists and writers. 

It has been featured in numerous works of literature, paintings, and sculptures as a symbol of the mysterious and unknown depths of the ocean. 

Model of an Oarfish at the Sant Hall of Oceans
Model of an Oarfish at the Sant Hall of Oceans / Tim Evanson via Wikimedia Commons CC A-SA 2.0

Oarfish are also considered bioindicator species, meaning their presence or behavior can provide clues about the health of the ocean environment. 

Changes in oarfish behavior or strandings may indicate shifts in oceanic conditions, making them important study subjects in marine biology and ecology. 

Humans rarely encounter oarfish due to their deep-sea habitat. 

When they do surface, they often make headlines, drawing the attention of scientists, fishermen, and the general public. 

Sightings of these majestic creatures generate excitement and wonder.

Future Prospects and Research

Oarfish have a long history of capturing the imagination of seafarers and coastal communities. 

While oarfish sightings remain rare, advancements in deep-sea exploration technology have enabled researchers to learn more about these elusive creatures. 

Pencil drawing of an Oarfish
Pencil drawing of an Oarfish / Freshwater and Marine Image Bank via Wikimedia Commons Public Domain

Understanding the behavior of oarfish is a key focus of current research. 

This research includes studying their feeding habits, migration patterns, and social behavior. 

By tracking the movements of tagged oarfish, scientists hope to gain insights into their mysterious lives in the deep ocean. 

DNA analysis of oarfish specimens can reveal valuable information about their evolutionary history and genetic diversity. 

This research can shed light on their relationships with other fish species and their adaptations to the extreme conditions of the deep sea. 

Improved underwater imaging and remote sensing technologies will allow researchers to capture high-resolution images and videos of oarfish in their natural habitat. 

This could reveal previously unknown behaviors and interactions. 

Juvenile oarfish
Juvenile oarfish / NMFS-PIRO Observer Program via Wikimedia Commons Public domain

Monitoring the ocean’s health and climate is crucial for understanding how it impacts oarfish populations. 

Advances in oceanographic research can provide valuable data on the changing conditions in the deep sea. 

International collaboration among researchers, marine biologists, and conservationists is essential to understanding oarfish comprehensively. 

Sharing data and resources can lead to more meaningful discoveries.


With its remarkable length, mysterious behavior, and deep-sea habitat, the oarfish continues to intrigue scientists and captivate the human imagination. 

Despite their elusiveness, advancements in technology and research have shed light on various aspects of these enigmatic creatures, from their taxonomy and physical characteristics to their role in deep-sea ecosystems. 

Oarfish are bioindicators of ocean health, making them valuable subjects for ecological studies. 

However, the challenges of understanding their behaviors, migration patterns, and population dynamics in the remote depths of the ocean highlight the need for continued research and international collaboration. 

As we delve deeper into the mysteries of the oarfish, we uncover their significance in marine ecosystems and their cultural and artistic importance, reminding us of the wonder and complexity of the world beneath the waves.


Q: Are oarfish dangerous to humans?

Oarfish are not considered dangerous to humans.

They are not known to be aggressive and do not possess any harmful features such as sharp teeth or venomous spines.

In fact, due to their deep-sea habitat and elusive nature, oarfish rarely come into contact with humans.

Q: Can oarfish survive if they are brought to the surface?

Oarfish are adapted to the high-pressure conditions of the deep sea, and when brought to the surface, they can suffer from depressurization, which can be fatal.

Most oarfish sightings occur when they wash ashore, often in a distressed or dying state.


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