Why are Stomias called scaly dragonfishes?

Their skin has small six-sided scales

Dragonfish

Q: How to identify Dragonfish?

Look at body shape, where the fins sit and their outline, mouth position, stripes and spots. Young fish and breeding adults can wear different patterns, and aquarium color varieties can look nothing like wild fish. Fish Identifier: upload a photo and compare the visible details.

Q: What does Dragonfish eat?

A deep-sea hunter that mostly eats other fish, plus some crustaceans. It sucks prey in, and its fangs stop it escaping.

Q: Are dragonfish dangerous to humans?

No. Dragonfish are small, about 32 cm at most for the boa dragonfish, and they live hundreds of metres down, far from swimmers. Their fangs are for small fish and crustaceans.

Q: Why do dragonfish glow?

They make their own light. The glowing chin barbel is thought to attract prey and signal to other dragonfish, and rows of belly lights probably help them blend in with faint light from above.

Q: Do dragonfish have see-through teeth?

Some do. A 2019 study found transparent teeth in the dragonfish Aristostomias scintillans, built from crystals about 20 nanometres across. Scaly dragonfishes (Stomias) have hinged fangs that fold inwards.

Q: How deep do dragonfish live?

The boa dragonfish has been found from 200 m to 2,173 m deep. It often swims up into the top 200 m at night to hunt.

Q: What do dragonfish eat?

Mainly other fish, plus crustaceans and sometimes squid. They suck prey in, and their fangs stop it escaping.

Q: Do dragonfish make red light?

Only a few relatives do, such as the stoplight loosejaw, whose red light peaks at about 705 nm. We found no report of red light in scaly dragonfishes (Stomias).

Q: Is the dragonfish endangered?

The boa dragonfish is listed as Least Concern (assessed 2013), though its population trend is unknown. Future deep-sea fishing and low-oxygen water are possible risks.

Q: What is the difference between a dragonfish and an anglerfish?

Both hunt with light, but in different ways. A dragonfish has a glowing barbel on its chin that it lights itself. A female anglerfish has a lure on a stalk on its head, lit by bacteria.

Stomias

Scaly dragonfishes (genus Stomias) are slender, dark predators of the deep ocean and part of the barbeled dragonfish family, Stomiidae. The best-known species, the boa dragonfish (Stomias boa), grows to about 32 cm and has been found between 200 and 2,173 m deep, rising towards the surface at night. A glowing barbel hangs from its chin, light organs line its belly, and its long fangs are hinged.

Also known as Scaly dragonfish, Boa dragonfish

Dragonfish abilities

Own light made by the fish, not by bacteriaStill debated
A glowing bulb dangles from the dragonfish's chin. Scientists think it draws prey closer in the dark, but its exact job is still a hypothesis.
- Nearly all barbeled dragonfishes have a glowing chin barbel. Researchers think it is used both to attract prey and to signal to other dragonfish.
- The light comes from the fish's own chemistry. Deep-sea anglerfish lures glow because of bacteria living inside them.
- Nobody has measured a flashing rhythm for Stomias, so the model shows a slow, steady pulse.
Sources [1, 3, 4, 5]
27× light-making evolved in fishes
Light organs along its sides and belly glow in the dark. Scientists think lights like these help a fish blend in with the faint light from above.
- A row of large photophores runs along each side, with smaller ones mostly on the belly.
- Organs near the eyes are reported to sense the light around the fish so it can adjust its own glow.
- Most deep-sea fish see best in blue, which matches most of the light animals make down there.
- Fishes have evolved light-making at least 27 separate times.
Sources [2, 5, 10]
1 row of hinged fangs on each jaw
An x-ray look at the fangs. They fold inwards to let prey in, then flick back up so it can't slip out.
- Scans of Stomias boa show that each fang is held on its inner side by a soft ligament that is not hardened into bone, so it can tip inwards.
- Upper and lower fangs alternate, and scientists compare the closed mouth to a cage.
- Another dragonfish, Aristostomias scintillans, has see-through teeth. Their enamel-like outer layer is made of crystals about 20 nanometres across, too small to scatter much light.
Sources [3, 6]
Up to 120° gape in related dragonfishes
To swallow big prey, the dragonfish tips its head back on a flexible neck and drops its jaw open very wide.
- Dragonfishes have a gap between the skull and the backbone where only a flexible rod (the notochord) remains.
- In Stomias boa, pads of tough tissue around this gap act like a double ball-and-socket joint and are thought to brace the neck when the mouth gapes.
- In related dragonfishes with a true head joint, the skull tips back farther than in any other bony fish, opening the mouth up to 120°.
Sources [7, 8, 9]
0–200 m where it was caught at night
By day Stomias waits in the deep. After dark it swims up towards the surface, where many small fish also gather at night.
- Stomias boa reportedly spends the day deeper than about 1,000 m and may swim up close to the surface at night.
- In the Northeast Atlantic, Stomias boa was the main fish hunter caught in the top 200 m at night.
- Not every dragonfish commutes. The stoplight loosejaw stays below about 500 to 600 m.
Sources [1, 11, 14, 16]
Fish main prey
Dragonfishes are among the top hunters of the twilight zone. They mostly eat other fish, sucking prey in as the mouth opens.
- Stomias boa eats midwater fishes and crustaceans.
- Dragonfishes take prey by suction, then their fangs keep it from escaping.
- As Stomias boa grows, it feeds higher up the food web.
Sources [1, 3, 14, 17]
<0.5% light reflected by ultra-black fishStill debated
Many deep-sea fish have ultra-black skin that swallows almost all light, hiding them from glowing searchlights. Whether Stomias has it has not been measured.
- In 2020 scientists found ultra-black skin in 16 deep-sea fish species from seven different groups, including a lure-bearing dragonfish.
- A tight layer of melanin packets in the skin traps light. Compared with skin that reflects 2% of light, an ultra-black fish can only be seen from a sixth of the distance, or less.
- Stomias are dark, but we found no study that measured their skin, so this ability is shown as a likely trick, not a fact.
Sources [13, 18, 19]
2,173 m deepest Stomias boa record
Stomias boa has been found from 200 m down to 2,173 m deep, far below where sunlight reaches.
- It usually lives much shallower than this, rising near the surface at night.
- It is found in deep oceans from 71°N to 50°S.
- Its relatives go deeper still: the stoplight loosejaw has been found to 3,886 m.
Deepest records
Boa dragonfish2,173 m
Stoplight loosejaw3,886 m
Humpback anglerfish4,500 m
Deepest known records; these fish usually live much shallower.
Sources [1, 2, 20, 21]

Tap a pin on the model or a part below.

Glowing bulb near the tip
- A long, fleshy barbel hangs from the chin. In Stomias boa it has a pale stalk, a dark spot at the base of the bulb and a dark filament at the end.
- A glowing chin barbel is the trademark of the barbeled dragonfishes, and nearly all of their closest relatives have one.
- The fish makes this light with its own body chemistry. Anglerfish lures, by contrast, are lit by bacteria.
- Scientists think the barbel helps attract prey and signal to other dragonfish, but nobody has filmed a Stomias using it.
Sources [1, 2, 3, 4, 5]
Hinged fangs fold inwards
- Stomias boa has one row of long, sharp fangs on each jaw, with gaps between them.
- On the inner side the fangs are held by a soft, flexible ligament, so they can fold inwards as prey slides in, then spring back up.
- Upper and lower fangs alternate, so a closed mouth works like a cage that stops prey slipping out.
- See-through teeth were studied in a different dragonfish, Aristostomias scintillans, not in Stomias.
Sources [3, 6]
Up to 120° gape in related dragonfishes
- In most fish the skull is firmly joined to the shoulder bones. In dragonfishes it is not, and there is a gap between skull and backbone.
- In Stomias boa, thick pads of tough tissue form a kind of double ball-and-socket joint for the head. Scientists think it braces the neck when the mouth opens extremely wide.
- In some related dragonfishes the head can be tipped back far enough for a gape of up to 120°, measured on museum specimens.
Sources [7, 8, 9]
- Most deep-sea fish see best in blue light, which matches the glow most deep-sea animals make.
- Behind each eye sits a large light organ. In Stomias, males reportedly have bigger eyes and bigger light organs there than females.
- Organs near the eyes are reported to sense the light around the fish, so it can adjust how bright its own lights shine.
- In the stoplight loosejaw, a relative, males have bigger eye lenses than females, which may help them spot females' lights.
Sources [2, 10, 11, 12]
27 times light-making evolved in fishes
- A row of large light organs, called photophores, runs along each side. Smaller ones are scattered in a geometric pattern, mostly on the belly.
- Like the barbel, they glow using the fish's own chemistry rather than borrowed bacteria.
- Light-making has evolved at least 27 separate times in fishes. Groups with their own built-in lights, like dragonfishes, have split into unusually many species.
Sources [2, 5]
- Stomias are called scaly dragonfishes: their dark skin is covered in small, six-sided scales.
- Some deep-sea fish have ultra-black skin that reflects less than 0.5% of light. We found no measurement for Stomias.
Sources [2, 13]
17–22 rays in the dorsal fin
- The dorsal fin on top and the anal fin underneath sit far back, close to the tail.
- Both fins are soft, with no spines: 17 to 22 rays on top and 18 to 22 underneath.
- The tail fin is forked.
Sources [2]
- Dragonfishes have a stretchy stomach that can hold large prey for their size.
- Stomias and its close relatives have no swim bladder, the gas bag many fish use to float.
- Dragonfishes mainly eat other fish. Some also take crustaceans and squid.
Sources [3, 7, 14]
32.2 cm longest Stomias boa
- The body is long, slim and snake-like. Its name boa comes from the snake.
- Stomias boa reaches 32.2 cm, measured without the tail fin. The longest species in the genus, Stomias longibarbatus, reaches 43 cm.
- Stomias is one genus in a family of more than 350 species of barbeled dragonfishes.
- Swordfish, deepwater hakes and blackmouth catsharks are among the predators known to eat it.
Sources [1, 2, 4, 15]

Real dragonfish

Expedition drawings and a museum model from Wikimedia Commons, because live dragonfish are rarely photographed. Five of them can repaint the 3D model.

Adult boa dragonfishLong, slim and dark, with small six-sided scales, a chin barbel with a glowing bulb and rows of light organs on the belly.Up to 32.2 cm; rises into the top 200 m at nightStomias boa, from Hickson's The Fauna of the Deep Sea (1893). Photo: Sydney John Hickson, Public domain
Adult boa dragonfishLong, slim and dark, with small six-sided scales, a chin barbel with a glowing bulb and rows of light organs on the belly.Up to 32.2 cm; rises into the top 200 m at nightStomias boa, painted for the Prince of Monaco's expeditions (1911). Photo: Erich Zugmayer, Public domain
Stomias longibarbatus, the longest Stomias, from Carl Chun's Valdivia expedition book (1903)Photo: Carl Chun, Public domain
Günther's boafish (Stomias affinis), from the Challenger expedition report (1887)Photo: R. Mintern, Public domain
Stoplight loosejaw (Malacosteus niger)A dark relative with a red light organ under each eye and a blue one behind it. Its red light peaks at about 705 nm.Up to 25.6 cm; stays deep (500–3,886 m) and sees red using a chlorophyll-based pigmentStoplight loosejaw (Malacosteus niger), from the Prince of Monaco's expeditions. Photo: Emma Kissling, Public domain
Stoplight loosejaw (Malacosteus niger)A dark relative with a red light organ under each eye and a blue one behind it. Its red light peaks at about 705 nm.Up to 25.6 cm; stays deep (500–3,886 m) and sees red using a chlorophyll-based pigmentStoplight loosejaw, from the Challenger expedition report (1887). Photo: R. Mintern, Public domain
Stoplight loosejaw (Malacosteus niger)A dark relative with a red light organ under each eye and a blue one behind it. Its red light peaks at about 705 nm.Up to 25.6 cm; stays deep (500–3,886 m) and sees red using a chlorophyll-based pigmentA model of a stoplight loosejaw at the Natural History Museum, London. Photo: Emőke Dénes, CC BY-SA 4.0

Dragonfish by the numbers

Measured by scientists on research ships and in museums. Some numbers come from close relatives, and we say so.

Length: 32.2 cm; longest Stomias boa, measured without the tail fin; The longest Stomias species reaches 43 cm⁠[1, 15]
Depth range: 200–2,173 m; where Stomias boa has been found⁠[1]
Night layer: 0–200 m; where Stomias boa was caught at night in the Northeast Atlantic⁠[14]
Range: 71°N–50°S; Stomias boa, in deep oceans⁠[1]
Stomias species: ≈11; FishBase lists 11; some scientists count fewer⁠[15, 11]
Dragonfish family: 350+; species of barbeled dragonfishes (Stomiidae)⁠[4]
Widest gape: 120°; in dragonfishes with a true head joint (not measured in Stomias)⁠[8]
Tooth crystals: ≈20 nm; crystal size in the see-through teeth of Aristostomias scintillans⁠[6]
Ultra-black skin: <0.5%; light reflected by 16 ultra-black deep-sea fishes (Stomias not tested)⁠[13]
Red light: ≈705 nm; peak of the stoplight loosejaw's red light organ⁠[24]

Dragonfish myths and facts

Deep-sea fish attract wild stories. Here is what the research says.

0 of 8 answered

“Dragonfish use red light like a sniper scope to spot prey.”
“A dragonfish's fangs can fold inwards.”
“Dragonfish unhinge their jaws like a snake.”
“Some dragonfish have see-through teeth.”
“The glowing chin barbel is proven to lure prey.”
“Dragonfish are giant sea monsters.”
“Dragonfish skin absorbs all light.”
“Dragonfish stay in the deep all the time.”

Dragonfish records

Superlatives from the dragonfish family and their deep-sea neighbours, each one sourced.

Widest-opening head
120°
Dragonfishes with a true head joint, such as loosejaws
Their skull tips back farther than in any other bony fish without such a joint, for a gape of up to 120°.⁠[8]
Only fish known to see with a chlorophyll pigment
Unique
Stoplight loosejaw
Its eyes use a pigment made from bacterial chlorophyll to pick up its own far-red light.⁠[10]
Biggest family in its order
350+ species
Barbeled dragonfishes (Stomiidae)
Of the 464 species of dragonfishes, bristlemouths, hatchetfishes and kin, more than 350 are barbeled dragonfishes.⁠[4, 19]
Longest scaly dragonfish
43 cm
Stomias longibarbatus
The longest species in the genus, measured without the tail fin.⁠[15]
Deepest boa dragonfish
2,173 m
Stomias boa
The deepest record for the species.⁠[1]
Darkest fish skin measured
0.044%
An Oneirodes anglerfish (not a dragonfish)
The darkest of the ultra-black deep-sea fishes found in 2020.⁠[18, 13]

A day in the life of a dragonfish

One boa dragonfish, 24 hours, and a long swim up and down.

Midday
Waiting in the deep
It spends the day deep down, reportedly often below 1,000 m, where sunlight barely reaches.⁠[1, 2]
Afternoon
Lights matched
Organs near its eyes reportedly sense the faint light, so it can adjust the glow of its belly lights.⁠[2]
Dusk
Going up
As the light above fades, it begins its climb towards the surface.⁠[1, 11]
Night
Top 200 m
In the Northeast Atlantic, it is the main fish hunter caught in the top 200 m at night.⁠[14]
Midnight
The lure glows
Its chin barbel glows in the dark. Scientists think the light may draw small fish closer.⁠[4, 3]
Strike
Folding fangs
It sucks prey in. Its fangs fold back to let it pass, then spring up again like a gate.⁠[3]
Later
Big gulp
Its head tips back on its flexible neck and the meal goes into its stretchy stomach.⁠[7, 3]
Before dawn
Back down
Before the sun rises, it sinks back into the deep for the day.⁠[1, 11]

Dragonfish vs stoplight loosejaw vs anglerfish

Three deep-sea hunters with glowing tricks, and three different ways to use them.

Boa dragonfish vs stoplight loosejaw vs humpback anglerfish
	Boa dragonfish	Stoplight loosejaw	Humpback anglerfish
Family⁠[1, 20, 21]	Barbeled dragonfishes (Stomias boa)	Barbeled dragonfishes (Malacosteus niger)	Deep-sea anglerfishes (Melanocetus johnsonii)
Size⁠[1, 20, 21]	Up to 32.2 cm	Up to 25.6 cm	Females 18 cm, males 2.9 cm
Depth range⁠[1, 20, 21]	200–2,173 m	500–3,886 m	100–4,500 m
Glowing tool⁠[2, 24, 21]	Glowing bulb on a chin barbel, plus belly lights	Red light organ under each eye, blue one behind	Lure on a long stalk on the head (female)
Light made by⁠[5, 24]	The fish itself	The fish itself (red probably made with filters)	Bacteria living in the lure
At night⁠[14, 16, 20]	Rises into the top 200 m	Stays below about 500–600 m	—
Food⁠[1, 20]	Midwater fishes and crustaceans	Crustaceans and fishes	—
Special trick⁠[3, 7, 10, 21]	Fangs fold inwards; head tips back	Sees its own red light	Lure stalk up to 61% of body length

Lengths are maximums, measured in slightly different ways. — means our sources did not cover it.

Is the dragonfish endangered?

Not as far as we know. But the deep ocean is changing, and people are eyeing its fish.

IUCN Red List

Least Concern (LC)

Trend unknown

Stomias boa is listed as Least Concern. It lives in deep oceans from 71°N to 50°S. Its population trend is not known.⁠[26, 1, 27]

IUCN Red List, assessed 2013 (Stomias boa)

Threats

Future fishing2–19.5 Gt
Twilight-zone fish may weigh 2 to 19.5 billion tonnes in total, and there is interest in catching them for fishmeal and supplements. FishBase rates Stomias boa as moderately vulnerable to fishing.⁠[28, 1]
Shrinking living space≈39%
Off California, one model projects the livable twilight zone could shrink by about 40 m (39%) by 2100 under high emissions, as low-oxygen water rises.⁠[29]
Big unknowns
Nobody knows how many dragonfish there are or whether their numbers are changing.⁠[26, 1]

What’s helping

High Seas Treaty2026
A United Nations agreement to protect marine life outside any country's waters came into force on 17 January 2026.⁠[30]
Science first
Researchers argue we need to know much more about twilight-zone fish and their food webs before they are fished.⁠[28]
New maps of the family
New studies in 2025 and 2026 are sorting out how the many dragonfishes are related and what they eat.⁠[4, 19, 14]

Dragonfish quiz

Twelve questions. Every answer is somewhere on this page.

Question 1 of 12Score 0

What hangs from a dragonfish's chin?

Dragonfish field notes

Diet, food web, safety and badges from the Snappit field guide.

Diet & Feeding

A deep-sea hunter that mostly eats other fish, plus some crustaceans. It sucks prey in, and its fangs stop it escaping.

Primary Foods

Lanternfish
Hatchetfish
Bristlemouth
Small crustaceans
Foraging Method: Ambush

Ecological connections

LanternfishHunts
Lanternfish are small twilight-zone fish, the kind of prey dragonfish eat.
HatchetfishHunts
Hatchetfish are small twilight-zone fish, also the kind of prey dragonfish eat.
BristlemouthHunts
Bristlemouths are tiny twilight-zone fish, also the kind of prey dragonfish eat.

Safety

Danger 1/5 · Very low

Dragonfish are not dangerous to humans, but they live in very deep parts of the ocean where it's hard for people to go.

Traits

Collections

Fish

Classification

Kingdom: Animalia
Phylum: Chordata
Class: Teleostei
Order: Stomiiformes
Family: Stomiidae
Genus: Stomias

Sources for these dragonfish facts

30 studies and references · checked Oct 16, 2026

Frequently Asked Questions

How to identify Dragonfish?

Look at body shape, where the fins sit and their outline, mouth position, stripes and spots. Young fish and breeding adults can wear different patterns, and aquarium color varieties can look nothing like wild fish. Fish Identifier: upload a photo and compare the visible details.

How long is Dragonfish?

15-35 cm

How much does Dragonfish weigh?

0.05-0.2 kg

How long does Dragonfish live?

10-15 years

What does Dragonfish eat?

A deep-sea hunter that mostly eats other fish, plus some crustaceans. It sucks prey in, and its fangs stop it escaping.

Where is Dragonfish usually found?

Deep Sea

How does Dragonfish hunt?

Ambush

How deep can Dragonfish go?

2173 m

Are dragonfish dangerous to humans?

No. Dragonfish are small, about 32 cm at most for the boa dragonfish, and they live hundreds of metres down, far from swimmers. Their fangs are for small fish and crustaceans.

Why do dragonfish glow?

They make their own light. The glowing chin barbel is thought to attract prey and signal to other dragonfish, and rows of belly lights probably help them blend in with faint light from above.

Do dragonfish have see-through teeth?

Some do. A 2019 study found transparent teeth in the dragonfish Aristostomias scintillans, built from crystals about 20 nanometres across. Scaly dragonfishes (Stomias) have hinged fangs that fold inwards.

How deep do dragonfish live?

The boa dragonfish has been found from 200 m to 2,173 m deep. It often swims up into the top 200 m at night to hunt.

What do dragonfish eat?

Mainly other fish, plus crustaceans and sometimes squid. They suck prey in, and their fangs stop it escaping.

Do dragonfish make red light?

Only a few relatives do, such as the stoplight loosejaw, whose red light peaks at about 705 nm. We found no report of red light in scaly dragonfishes (Stomias).

Is the dragonfish endangered?

The boa dragonfish is listed as Least Concern (assessed 2013), though its population trend is unknown. Future deep-sea fishing and low-oxygen water are possible risks.

What is the difference between a dragonfish and an anglerfish?

Both hunt with light, but in different ways. A dragonfish has a glowing barbel on its chin that it lights itself. A female anglerfish has a lure on a stalk on its head, lit by bacteria.

Take the discovery with you