T
Species Profile

Tire Track Eel

Mastacembelus armatus

Tire-track camo, night-stalking hunter
iStock.com/Miropa

Tire Track Eel Distribution

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This map shows coastal regions where Tire Track Eel are found.

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A Tire Track Eel resting on the bottom of a freshwater aquarium

At a Glance

Wild Species
Also Known As Zigzag eel, Zig-zag eel, Zigzag spiny eel, Indian spiny eel, Asian spiny eel
Diet Carnivore
Activity Nocturnal+
Lifespan 12 years
Weight 2.5 lbs
Status Least Concern
Did You Know?

Maximum reported size is 90 cm total length (FishBase), far larger than most home aquaria accommodate.

Scientific Classification

A freshwater spiny eel from South Asia known for its elongated body and maze-like “tire track” pattern. Despite the name, it’s not a true eel. It is a nocturnal, bottom-oriented predator that burrows and can grow quite large, making it challenging for small aquaria.

Kingdom
Animalia
Phylum
Chordata
Class
Actinopterygii
Order
Synbranchiformes
Family
Mastacembelidae
Genus
Mastacembelus
Species
armatus

Distinguishing Features

  • Elongated body with long dorsal fin base
  • Small spines preceding the dorsal fin
  • Labyrinthine “tire track” flank pattern
  • Downturned mouth adapted for probing substrate

Physical Measurements

Length
1 ft 12 in (12 in – 2 ft 11 in)
Weight
2 lbs (0 lbs – 6 lbs)
Top Speed
4 mph
swimming

Appearance

Primary Colors
Secondary Colors
Skin Type Mucous skin
Distinctive Features
  • Elongated, eel-like body; not a true eel (Synbranchiformes).
  • Maximum reported total length 90 cm TL (Froese & Pauly, FishBase).
  • Long pointed snout with small terminal mouth for picking benthic prey.
  • Numerous isolated dorsal spines precede the long soft dorsal fin.
  • Labyrinthine dark lines and ocellated blotches give a tire-track look.
  • Small, embedded scales; skin feels smooth and heavily mucus-coated.
  • Nocturnal, bottom-oriented predator; hides by day and burrows in sand.
  • Anal and dorsal fins long and low, running much of body length.

Sexual Dimorphism

Sexual dimorphism is weak and mostly seasonal. Females become deeper-bodied and heavier when gravid, while males tend to remain slimmer with a more streamlined abdomen; consistent color differences are not reliable.

  • Males usually slimmer-bodied, especially outside peak feeding periods.
  • Females become noticeably deeper-bodied when carrying mature eggs.

Did You Know?

Maximum reported size is 90 cm total length (FishBase), far larger than most home aquaria accommodate.

Despite the name, it's a spiny eel (Mastacembelidae), not a true eel from order Anguilliformes.

It hunts mostly at night, using ambush strikes from sand or mud to grab worms, insects, and small fish.

The maze-like "tire track" pattern is common in juveniles and helps camouflage against leaf litter and mottled substrates.

It occurs across the Indian subcontinent, recorded from freshwater rivers, floodplains, canals, and reservoirs (regional faunal records).

Mastacembelids have isolated dorsal spines before the soft dorsal fin-an "armed" feature echoed by the species name armatus.

Unique Adaptations

  • Isolated dorsal spines provide defense and make extraction by predators difficult once wedged in crevices.
  • Elongated, flexible body and reduced pelvic fins enable efficient sand-burrowing and tight-space navigation.
  • Cryptic tire-track pattern breaks up the body outline against rippled substrates and tangled detritus.
  • Bottom-oriented sensory focus: taste and touch around the snout help locate prey in turbid, low-light habitats.

Interesting Behaviors

  • Burrows tail-first into sand or mud, often leaving only the snout exposed for breathing and ambush.
  • Nocturnal foraging peaks after lights-out; it patrols bottoms and edges rather than open water.
  • Shows strong shelter fidelity, repeatedly returning to the same burrow, pipe, or root tangle.
  • Rapid "S-curve" strikes allow it to seize prey from cover with minimal body exposure.
  • Can be secretive by day, remaining motionless for hours, then becoming an active hunter at dusk.

Cultural Significance

Often treated as a "freshwater eel" in South Asian fish markets and aquaria. Its striking pattern fuels the "tire track" trade name, while its large adult size makes it a challenging, conversation-starting display fish.

Myths & Legends

The genus name is a classical naming story: Greek mastax ("mouth") + kembelos ("curved"), describing a snout built for probing prey.

The species epithet armatus ("armed") is a traditional naturalists' label referring to the defensive dorsal spines along its back.

In aquarium folklore, "tire track eels" are said to be "ghost fish" by day-vanishing into sand and reappearing at dusk in the same spot.

Conservation Status

LC Least Concern

Widespread and abundant in the wild.

Population Unknown

Life Cycle

Birth 8000 frys
Lifespan 12 years

Lifespan

In the Wild
7–18 years
In Captivity
10–20 years

Reproduction

Mating System Promiscuity
Social Structure Solitary
Breeding Season Monsoon/rainy season (roughly June-September)
Breeding Pattern Transient
Fertilization Substrate Spawning
Birth Type Substrate_spawning

Mastacembelus armatus is an oviparous freshwater fish (reported to reach ~90 cm TL) that likely forms brief spawning encounters during seasonal rains, releasing externally fertilized, demersal adhesive eggs onto vegetation/substrate; parental care is not reported.

Behavior & Ecology

Social Solitary Group: 1
Activity Nocturnal, Crepuscular
Diet Carnivore earthworms
Seasonal Hibernates

Temperament

Secretive
Territorial
Predatory
Stress-prone

Communication

none documented
chemical cues
body language
tactile contact
lateral-line sensing

Habitat

Biomes:
Freshwater Wetland Tropical Dry Forest Tropical Rainforest
Terrain:
Riverine Plains Valley Hilly Muddy Sandy Rocky +1
Elevation: Up to 3280 ft 10 in

Ecological Role

Nocturnal benthic mesopredator regulating invertebrates and small fishes in South Asian rivers.

invertebrate control trophic transfer prey base support

Diet Details

Main Prey:
Chironomid larvae Aquatic insect larvae Earthworm Oligochaete worms Freshwater shrimp Small fish

Human Interaction

Domestication Status

Wild

Wild South Asian freshwater fish; not domesticated. Mostly wild-caught for aquarium trade and local food fisheries. Reported to reach 90 cm TL and be nocturnal burrower (FishBase); no established captive-breeding domestication program.

Danger Level

Low
  • Painful dorsal-spine punctures
  • Bites when handled
  • Injury during netting
  • Allergic reaction to mucus

As a Pet

Suitable as Pet

Legality: Generally legal; local invasive-species rules may apply.

Care Level: Expert Only

Purchase Cost: $15 - $120
Lifetime Cost: $2,500 - $12,000

Economic Value

Uses:
Aquarium Fisheries Trade
Products:
  • ornamental
  • food

Relationships

Predators 4

Goonch catfish
Goonch catfish Bagarius bagarius
Freshwater shark
Freshwater shark Wallago attu
Great snakehead Channa marulius
Mugger crocodile Crocodylus palustris

Related Species 4

Fire eel
Fire eel Mastacembelus erythrotaenia Shared Genus
Day's spiny eel Mastacembelus dayi Shared Genus
Bengal spiny eel Macrognathus pancalus Shared Family
Peacock spiny eel Macrognathus siamensis Shared Family

Ecological Equivalents 3

Animals that fill a similar ecological role in their ecosystem

Swamp eel Ophichthys cuchia Nocturnal, burrowing freshwater predator that occupies riverine lowland habitats in South Asia.
Asian spiny eel
Asian spiny eel Macrognathus aculeatus Feeds on benthic invertebrates and fish; hides in substrate and forages at night.
Spiny eel Mastacembelus armatus Bottom-oriented, nocturnal predator. Reported to 90 cm total length (FishBase). Burrows in sand and mud.

The tire track eel gets its name from the dark, splotchy pattern on its long back that looks a lot like a tire tread. This eel lives in rivers and marshes in Southeast Asia. It’s a popular pet for people who own large freshwater aquariums. This carnivorous eel can be as long as 2.4 feet full-grown.

3 Tire Track Eel Facts

  1. Sneaky eels: These eels are fast swimmers that sometimes steal food out of the mouths of other fish in an aquarium.
  2. Spiny eel: These types of eel are also referred to as spiny eels because of the collection of spines near their dorsal fin.
  3. Poor vision: These eels are known for their poor vision. But they have a sense of smell that helps them find food at night.

Classification and Scientific Name

The scientific name for these eels is Mastacembelus favus. They are also known as spiny eels. They are in the Actinopterygii class and the Mastacembelidae family. When broken down, the Latin word Mastacembelidae loosely translates to the phrase: Throws itself forward to bite.

The Different Species

These eels belong to the Mastacembelidae family, containing 93 species of eel. These eels are also known as spiny eels.

Other spiny eels include:

  • Fire eel (Mastacembelus erythrotaenia): It’s found in the same area of the world as the tire track eel. At almost four feet long full-grown, these eels are much longer than tire track eels.
  • Peacock eel (Macrognathus siamensis): This is another spiny eel found in Southeast Asia. It’s nocturnal like the tire track eel, but only reaches a length of one foot full-grown.
  • Half-banded eel (Macrognathus pancalus): The half-banded eel is eight inches in length when fully grown. It has a pointed snout like a tire track eel with a pattern of dark bands curving over its back.

Appearance

The first notable thing about these eels is the pattern of color on their skin. The lines of splotches bring to mind tire tread marks. Their skin is a combination of tan with dark brown markings.

These eels have pointed snouts so they can easily poke their heads into narrow spaces. Their size ranges from 0.5 to 2.4 feet long, and they weigh from three to five pounds.

Tire track eels have spines that can deter larger fish from trying to attack. Also, this eel can slip into narrow spaces between rocks to escape predators. The dark color of these eels serves as camouflage in their habitat.

Tire Track Eels have pointed snouts that let them poke into tight crevasses.

Tire Track Eels have pointed snouts that let them poke into tight crevices.

Distribution, Population, and Habitat

Tire track eels live in Southeast Asia, specifically Cambodia, Malaysia, Thailand, and Vietnam. They live in inland freshwater streams, rivers, and marshes. This eel hides under the sand or rocky bottom of its habitat by day and comes out to hunt at night.

The total number of tire track eels is unknown, but its population is stable. It has a conservation listing of Least Concern.

Predators and Prey

Tire track eels are mainly carnivores, though some eat vegetation. They use their strong jaws to latch onto their prey.

What eats tire track eels?

Seabirds such as bitterns and herons, as well as larger eels, eat these eels. Large fish like the kelah may eat eel eggs.

Humans are predators of this eel as well. They’re captured in order to be sold as pets. They’re usually sold by fish stores at a price of around $25. Despite being sold as pets, these eels are categorized as Least Concern.

What do tire track eels eat?

These eels eat worms, krill, shrimp, and plankton.

Reproduction and Lifespan

In the wild, a male tire track eel chases a female for hours before mating. They may continually circle each other during the breeding period. After mating, the female releases her eggs into clumps of floating vegetation. These eels can lay from 700 to 1000 eggs. She doesn’t provide any protection or care for the eggs. They hatch in three to four days.

Breeding these eels in captivity is very difficult. For one thing, in the wild, the beginning of flood season serves as the signal for these eels to breed. Secondly, the lack of space in a tank makes it challenging to mimic this eel’s natural habitat. Another issue with breeding is that there’s no easy way for an owner to determine the sex of this eel.

Tire track eels have a lifespan of eight to eighteen years.

Tire Track Eel in Fishing

These eels are caught in order to be sold to people who own large aquariums. They are captured in traps placed in their habitat. Then, they’re shipped to various fish stores to sell to aquarium enthusiasts.

Many people like to keep this variety of eels in large home aquariums because of their attractive patterns. Also, though these eels like to hide, they can be interesting to watch.

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Sources

  1. Quality Marine / Accessed April 8, 2022
  2. Ecology Asia / Accessed April 8, 2022
  3. Fish Tank Advisor / Accessed April 8, 2022
  4. Nayturr / Accessed April 8, 2022
  5. Aqua Fish / Accessed April 8, 2022
  6. Wikipedia / Accessed April 8, 2022
A-Z Animals Staff

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A-Z Animals Staff

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Tire Track Eel FAQs (Frequently Asked Questions)

These eels are found in Southeast Asia. Specifically, they live in rivers, streams, and marshes in Thailand, Vietnam, Malaysia, and Cambodia.