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Species Profile

Escolar

Lepidocybium flavobrunneum

Deep-sea predator with a notorious bite
Intellegent Design/Shutterstock.com

Escolar Ocean Range

Marine Species

Escolar (Lepidocybium flavobrunneum) is an oceanic deep-water fish found worldwide in tropical to warm-temperate Atlantic (including the Caribbean Sea and Gulf of Mexico), Pacific, Indian oceans, and reported from the Red Sea. It lives mainly 200–885 m (mesopelagic to bathypelagic), moves shallower at night, and is not coastal but found over deep waters, seamounts, and upper continental slopes.

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Ocean Regions 10

atlantic_ocean north_atlantic south_atlantic caribbean_sea gulf_of_mexico pacific_ocean north_pacific south_pacific indian_ocean red_sea
drawing of escolar fish

At a Glance

Ocean Species
Also Known As butterfish, white tuna, walu, gempachi
Diet Carnivore
Activity Nocturnal+
Lifespan 10 years
Weight 45 lbs
Status Least Concern
Did You Know?

Maximum reported size is about 200 cm total length (TL) (FishBase species account).

Scientific Classification

Escolar is a large, deep-water, oceanic predatory ray-finned fish in the family Gempylidae (snake mackerels). It is widely distributed in tropical and warm-temperate seas and is well known in the seafood trade.

Kingdom
Animalia
Phylum
Chordata
Class
Actinopterygii
Order
Scombriformes
Family
Gempylidae
Genus
Lepidocybium
Species
Lepidocybium flavobrunneum

Distinguishing Features

  • Elongate, dark brown to nearly black body typical of gempylids
  • Oceanic, deep-water lifestyle; predatory on smaller fishes and cephalopods
  • Notable for very high wax-ester (indigestible lipid) content in flesh, which is responsible for well-known dietary effects when eaten in quantity

Physical Measurements

Length
3 ft 11 in (2 ft 7 in – 6 ft 7 in)
Weight
44 lbs (11 lbs – 99 lbs)
Poisonous

Appearance

Primary Colors
Secondary Colors
Skin Type Covered with very small, fine scales typical of the snake mackerel family (often giving a smooth-to-the-touch appearance); skin and flesh are notably oily/waxy due to high wax-ester content (a trade/food-safety-relevant trait, not a visible pattern).
Distinctive Features
  • Deep-water pelagic predator (mesopelagic to bathypelagic); commonly reported from ~200-885 m depth range (FishBase summary of compiled records).
  • Large, elongate, laterally compressed "snake mackerel" body form (snake mackerel family), built for cruising and ambush predation on fishes and cephalopods.
  • Very large eyes relative to head (deep-water adaptation).
  • Long-based dorsal fin profile typical of gempylids; fins generally dark brown to blackish, blending with body coloration.
  • Caudal peduncle with keels typical of scombriform swimmers; tail forked, aiding sustained swimming.
  • Often confused with oilfish, escolar is usually uniformly dark brown or black and slimmer; oilfish is thicker-bodied. Use taxonomic keys (fin/scale counts and body shape), not color alone.

Did You Know?

Maximum reported size is about 200 cm total length (TL) (FishBase species account).

It's a deep-water pelagic predator, commonly captured hundreds of meters down; it also rises toward the surface at night (diel vertical migration) (FishBase; fisheries observations).

Escolar flesh can contain very high levels of indigestible wax esters (gempylotoxins), which can cause keriorrhea (oily, orange diarrhea) when eaten in quantity-one reason it's controversial in seafood markets.

It's in family Gempylidae ("snake mackerels"), a group of streamlined midwater hunters that includes oilfish (Ruvettus pretiosus) and several long-bodied, fang-toothed predators.

The species is widely distributed across tropical and warm-temperate oceans worldwide (oceanic, not coastal).

Escolar is frequently misidentified/mislabeled in trade (e.g., as "white tuna," "butterfish," or "walu"), which matters because consumption advisories differ by species.

Unique Adaptations

  • High lipid/wax-ester content in tissues (a feature shared with some gempylids) contributes to buoyancy/energy storage in the deep ocean-but is poorly digested by humans.
  • Streamlined, muscular body with a narrow caudal peduncle suited for burst swimming and pursuit in open water.
  • Large eyes relative to many surface predators, improving vision in low-light depths.
  • Predatory jaw and teeth adapted for grasping slippery prey like squid and midwater fishes.
  • Physiology suited to broad vertical habitat use (from deep daytime layers to shallower nighttime layers) typical of many mesopelagic predators.

Interesting Behaviors

  • Diel vertical migration: tends to stay deep by day and move shallower at night, likely tracking prey that migrates upward after dusk.
  • Opportunistic predation on midwater fishes and cephalopods; its body form and dentition fit ambush-and-chase feeding in the twilight zone.
  • Oceanic roaming: individuals are typically encountered far from shore over deep water rather than on reefs or in estuaries.
  • Often caught as bycatch on pelagic longlines targeting tuna/swordfish-its behavior overlaps with these fisheries in deep, open-water sets.
  • Handles low-light hunting: large eyes and deep-water habits suggest reliance on vision in dim mesopelagic conditions.

Cultural Significance

Escolar (Lepidocybium flavobrunneum) is widely sold, often as "white tuna" in sushi. Its wax esters can cause stomach upset, so some countries and sellers require warnings or limits. It shows problems with fish tracking, mislabeling, and clear labels, and is like oilfish (Ruvettus pretiosus).

Myths & Legends

In many places, restaurants call escolar (Lepidocybium flavobrunneum) "white tuna." This name spread in sushi bars even though it is not a true tuna (Scombridae), and diners often hear this story.

Modern caution stories in fishing ports and sushi cities warn that escolar (Lepidocybium flavobrunneum) can make you leak orange oil; these tales act as new legends about its wax-ester-rich flesh.

The name 'escolar' is used in markets as a fancy trade name and tied to stories of a buttery texture, which keep going even where warnings say eat small portions and labels are clear.

Conservation Status

LC Least Concern

Widespread and abundant in the wild.

Population Unknown

Life Cycle

Lifespan 10 years

Lifespan

In the Wild
6–14 years
In Captivity
0.5–2 years

Reproduction

Mating System Promiscuity
Social Structure Solitary
Breeding Pattern Transient
Fertilization Broadcast Spawning
Birth Type Broadcast_spawning

Direct mating behavior of Escolar (Lepidocybium flavobrunneum) is poorly known. Solitary, deep-water pelagic fish likely have brief, opportunistic mating, with external fertilization and pelagic broadcast spawning; eggs and larvae drift with no parental care.

Behavior & Ecology

Social Solitary Group: 1
Activity Nocturnal, Crepuscular
Diet Carnivore Fishes and oceanic squids (dominant prey categories reported in stomach-contents summaries)

Temperament

Predatory and piscivorous/teuthophagous (feeds on fishes and cephalopods); behavior consistent with an active ambush/roving predator in midwater (Nakamura & Parin, 1993; FishBase).
Generally non-territorial and not known to maintain stable social bonds; interactions are expected to be brief and resource-driven (typical of many oceanic gempylids; Nakamura & Parin, 1993).
Escolar (Lepidocybium flavobrunneum) likely makes daily up-and-down movements: deep by day, shallower at night or dusk/dawn like many mesopelagic predators; detailed in-water behavior data are limited.
For Escolar (Lepidocybium flavobrunneum), maximum age is not confirmed by scientific age-and-growth studies; many sources list a maximum length of about 200 cm but give no proven maximum age.

Communication

No species-specific sound production is documented in standard references; acoustic communication is not known/confirmed for Lepidocybium flavobrunneum FAO; Nakamura & Parin, 1993; FishBase
Hydrodynamic/mechanosensory signaling via the lateral line Near-field water movement detection) likely mediates short-range interaction/avoidance, as in most teleost fishes (general teleost sensory biology; species-specific studies lacking
Visual cues at close range when within sufficiently lit depths or during night-time ascents into brighter upper layers; coordination, if any, is expected to be loose rather than synchronized schooling FishBase; Nakamura & Parin, 1993
Chemical cues (olfaction) for prey detection and possibly reproductive signaling; direct evidence for social chemical signaling in this species is not available in standard species accounts.

Habitat

Open Ocean Deep Sea
Biomes:
Elevation: Up to 3608 ft 11 in

Ecological Role

Mid-to-upper trophic-level oceanic mesopelagic predator linking midwater nekton (lanternfishes/squids) to larger pelagic predators.

Regulates populations of midwater nekton (especially small fishes and squids) through predation Transfers energy from mesopelagic prey layers to higher trophic levels (tunas, billfishes, large sharks) that consume escolar Contributes to pelagic food-web stability by coupling diel-vertically migrating prey with oceanic predator communities

Diet Details

Main Prey:
Mesopelagic fishes Pelagic fish Cephalopods Pelagic crustaceans

Human Interaction

Domestication Status

Wild

Escolar (Lepidocybium flavobrunneum; Family Gempylidae) is not domesticated and has no aquaculture. It is an oceanic, deep-water predator (mesopelagic/bathypelagic) found in tropical and warm-temperate seas. Humans catch it in offshore fisheries (pelagic longlines; often bycatch in tuna/billfish gears). It can reach about 200 cm TL; lifespan and growth are uncertain.

Danger Level

Moderate
  • Foodborne illness: escolar flesh can contain high levels of indigestible wax esters (commonly referred to as 'gempylotoxin'), which can cause keriorrhea (oily orange diarrhea) and gastrointestinal distress when eaten in typical portion sizes; this is a well-documented human interaction driver and the basis for advisories/labeling concerns in multiple countries.
  • Handling/injury risk typical of large offshore fishes during capture (hooks, gaffing, deck injuries), especially when taken on longlines.
  • General seafood safety risk if temperature-abused (e.g., potential histamine/scombroid-type illness in mishandled dark-meat pelagic fishes), though this is a handling issue rather than a species-specific venom/toxin hazard from contact.

As a Pet

Not Suitable as Pet

Legality: Escolar (Lepidocybium flavobrunneum) is not a practical pet. Laws usually treat it under marine collection and import and food fish rules. It grows to about 200 cm, is pelagic, needs high oxygen and ranges widely.

Care Level: Expert Only

Purchase Cost:
Lifetime Cost:

Economic Value

Uses:
Commercial fishing (food) Seafood trade/retail Bycatch in pelagic longline fisheries Food safety monitoring and labeling policy
Products:
  • Fresh/frozen fillets and steaks (often marketed under names such as 'escolar', and sometimes misrepresented as 'white tuna')
  • Smoked/processed fish products
  • Restaurant/retail seafood items (with consumer advisories in some markets due to digestive effects)

Relationships

Related Species 6

Oilfish
Oilfish Ruvettus pretiosus Shared Family
Snake mackerel Gempylus serpens Shared Family
Silver gemfish Rexea solandri Shared Family
Gemfish Rexea prometheoides Shared Family
Black gemfish Nesiarchus nasutus Shared Family
Snoek Thyrsites atun Shared Family

The escolar is one of the best-tasting fish around, and its nutritional values are high. However, if you eat too much of it, you might pay with cramping diarrhea! Though you should only eat a little of this fish at a time, it is often mislabeled as something else, and that can lead to problems. But it’s not the fish’s fault. Read on for more info on the escolar.

Five Amazing Facts About the Escolar

Escolar Fish

Despite being a popular ingredient in nigiri sushi, sushi rolls, and sashimi, escolar is ironically prohibited in Japan due to its adverse health effects.

  1. Ironically, though escolar is used in nigiri sushi, sushi rolls, and sashimi, it is banned in Japan because of its health effects.
  2. It is often sold erroneously as “white tuna.”
  3. Though some people suffer diarrhea if they eat too much escolar, others experience a distressing seepage of orange oil.
  4. The fish has rings around its eyes that look like eyeglasses, so its common name is Spanish for “scholar.”
  5. The fish stores the waxy esters it can’t digest in its body, and as much as 20 percent of its weight can be made up of these compounds.

Evolution and Origins

The term “escolar” originates from Spanish, as the rings around the eyes of the fish bear a resemblance to the spectacles worn by scholars, hence its association with the word “scholar.” It is also related to the term “doublet” of scholars.

The escolar is commonly encountered in deep tropical and temperate waters worldwide, with depths ranging from 200 to 885 meters, and it is frequently caught in the coastal waters of Australia and New Zealand.

It is valued as a food source in various European, Asian, and American countries, similar to its relative, the oilfish.

Classification and Scientific Name

The scientific name of the escolar is Lepidocybium flavobrunneum. The genus name comes from the Greek words lepis, which means “scale” and kybion, which means “tuna.”

The species name comes from the Latin words flavo, which means “yellow,” and brunneum, which means “brown.” So the name can be translated as a “scaly, yellow-brown tuna.”

Appearance

The escolar, while not the prettiest of fish, can grow to nearly 7 feet in length and weigh as much as 99 pounds. It has a fusiform body and a superior mouth, which means that its lower jaw juts out beyond its upper jaw. There are small teeth in the lower jaw, and the upper jaw boasts two pairs of fangs. Younger fish are brown or gray and become black as they get older.

It has an interesting sideways keel on the root of its tail that’s lined by smaller keels both above and below it. It also has eight to nine dorsal spines, 16 to 18 soft rays on its back, one or two anal spines, and 12 to 14 soft rays in the same area.

Since it lives deep in the ocean where light is faint, the escolar has large eyes to help it see. Its dark coloration also camouflages it from both prey and predators.

drawing of escolar fish

Escolar is a type of snake mackerel.

Distribution, Population, and Habitat

The escolar is found in the mesopelagic and epipelagic zones of warmer seas. The mesopelagic zone is also called the ocean’s twilight zone and is found between 660 to 3300 feet below the surface. The epipelagic zone is the top layer of the ocean and receives sunlight.

The fish is known for staying in the mesopelagic zone during the day and then rising to the epipelagic zone at night. It is often part of a tuna bycatch and is most often found near ridges, underwater cliffs, and ledges. It seems especially abundant around Japan, Korea, the United States, and Italy.

Predators and Prey

The escolar’s prey includes other fish such as mackerel, tuna, bonito, pomfrets, dolphinfish, and types of oarfish. They also eat squid and crustaceans. Though it can swim fast, biologists believe that this fish waits for its prey to pass within striking distance. It then grabs and eats it.

One fish that preys on the escolar is the yellowfin tuna, which can weigh twice as much as the escolar. Humans, of course, are also predators of the escolar.

Reproduction and Lifespan

Oilfish

Eating oilfish meat can cause symptoms like severe diarrhea, nausea, and vomiting in some people.

Not much is known about the escolar’s reproduction, but it’s believed that they probably spawn in May and/or November. It’s also probable that the fish migrates long distances to reach its spawning or feeding areas. Though escolar is solitary for most of its life, it can be found in numbers in these areas.

Scientists also know that the escolar is oviparous, which means it lays eggs. The female deposits as many as 300,000 eggs into the water, while the male deposits sperm. The eggs are then fertilized and become part of the plankton.

Biologists believe that escolars are ready to breed when they’re between 0.98 and 1.15 feet long. They appear to have a lifespan longer than 11 years.

Fishing and Cooking

escolar being used in sushi

Escolar is used in sushi.

Many people who have tasted escolar swear that it’s the best fish they’ve ever had, with a rich, silken texture that rivals that of the best quality tuna. Besides sushi rolls, nigiri sushi, and sashimi, it can be broiled, baked, grilled, poached, steamed, and sautéed.

The nutrition provided by the fish is admirable. Six ounces of escolar have 354 calories, 30 grams of protein, 23.4 grams of fat, and 175 milligrams of sodium.

Despite its great taste and the nutrition found in the meat, it needs to be eaten sparingly to avoid the discussed side effects. These side effects can kick in as early as half an hour after eating too much of this fish.

Population

The population of this fish isn’t precisely known, but its conservation status is of least concern.

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Sources

  1. Kidadl / Accessed March 5, 2022
  2. Chefs Resources / Accessed March 5, 2022
  3. Sea Grant / Accessed March 5, 2022
  4. ITIS / Accessed March 5, 2022
  5. Global Seafoods / Accessed March 5, 2022
  6. Fishbase / Accessed March 5, 2022
  7. Wikipedia / Accessed March 5, 2022
Austin S.

About the Author

Austin S.

Growing up in rural New England on a small scale farm gave me a lifelong passion for animals. I love learning about new wild animal species, habitats, animal evolutions, dogs, cats, and more. I've always been surrounded by pets and believe the best dog and best cat products are important to keeping our animals happy and healthy. It's my mission to help you learn more about wild animals, and how to care for your pets better with carefully reviewed products.
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Escolar FAQs (Frequently Asked Questions)

An escolar is a fish that lives deep in the ocean that is known for the delicious taste of its meat and for the fact that the meat can give a person the trots.