Tire Track Eel

Mastacembelus armatus

Oddballs

A massive, predatory spiny eel known for its distinctive tire-track patterning. They are nocturnal bottom-dwellers that love to burrow. A soft sand substrate is absolutely mandatory; sharp gravel will severely damage their skin and lead to fatal bacterial infections. While peaceful to fish too large to swallow, they are highly efficient predators that will eat any tank mate that fits into their surprisingly large mouths. Excellent escape artists; a heavy, tight-fitting lid is required.

At a Glance

Adult Size75 cm
Body ShapeEel
Growth RateModerate
TemperamentSemi-Aggressive
Water TypeFreshwater Only
Flow PreferenceModerate
Waste OutputHigh
StockingSolo only

Tank Requirements

Minimum Volume680 L
Minimum Length180 cm
FlowModerate
Water TypeFreshwater Only
Must-Haves in the Tank
Sand (Sifters)Smooth Gravel (Sensitive Barbels)Driftwood (Digestion/Hiding)

Water Parameters

Temperature2228°C
pH6.57.5
Hardness515 dGH

Temperament & Compatibility

Aggression LevelSemi-Aggressive
6/10
Where They Swim
Surface
Mid-level
Bottom
Stocking Guidelines
Keep at Least1 (solo is fine)
Max per Tank1
Can Live Alone?Yes
Behavior Traits
Piscivore (Eats small/nano fish)Shrimp EaterDigger (Disturbs Substrate)Jumper (Lid Required)NocturnalAggressive to same species/look-alikes

Available Varieties

Each variety inherits the species defaults above. Only differences are highlighted.

Standard / Adult

The fully grown adult form. Requires a massive tank with a substantial footprint to maneuver. Very intolerant of other spiny eels at this size; best kept as a solitary bottom-dweller with large, peaceful mid-water or top-dwelling fish.

Differs in 1 trait from base species

Also known as: Full Grown, Adult Tire Track Eel

Behavior Traits
Piscivore (Eats small/nano fish)Shrimp EaterDigger (Disturbs Substrate)Jumper (Lid Required)NocturnalAggressive to same species/look-alikesTerritorial (Defends specific area)

Juvenile (Grow-out)

Sold at a small size (typically 10-15cm) but grows rapidly. A juvenile can temporarily reside in a smaller grow-out tank (55+ gallons) but will quickly require a permanent massive enclosure. They must be kept on soft sand even as babies to practice burrowing.

Differs in 4 traits from base species

Also known as: Baby Eel, Small Spiny Eel

Adult Size15 cm
Min Volume200 L
Min Length120 cm
Growth RateFast

Tire Track Eel Care Guide Summary

The Tire Track Eel, scientifically known as Mastacembelus armatus, belongs to the Oddballs family group. Adults reach a maximum size of approximately 75 cm and have a eel body shape with a moderate growth rate. Classified as semi-aggressive, this species primarily occupies the bottom zone of the aquarium and produces a high level of biological waste.

To thrive, the Tire Track Eel requires a freshwater only aquarium with a minimum volume of 680 litres and a tank length of at least 180 cm. Water temperature should be maintained between 22°C and 28°C, with a pH range of 6.57.5 and a general hardness of 515 dGH. A moderate water flow is preferred.

Due to its specialist needs, the Tire Track Eel is best suited for fishkeepers who can provide a carefully planned setup. This species is available in 2 varieties: Standard / Adult and Juvenile (Grow-out). Each may differ slightly in size, temperament, or care needs, so it is worth checking the specific requirements of the variety you plan to keep.

Tire Track Eel Habitat Setup

When setting up an aquarium for the Tire Track Eel, a moderate water flow best suits their natural preferences. Because this species occupies the bottom zone, the aquarium layout should prioritise sufficient floor space with hiding spots among rocks, wood, or dense planting. Useful additions include a sand substrate to accommodate their sifting behaviour, smooth gravel or rounded substrate to protect their sensitive barbels, and driftwood, which can serve as both a hiding place and a dietary supplement. Keepers should note that a tight-fitting lid is essential, as this species is a known jumper and expect substrate disturbance, so lightweight décor should be secured.

Tire Track Eel Compatibility Notes

Classified as semi-aggressive, the Tire Track Eel is best housed alone, as they do not tolerate others of their kind in confined spaces. When choosing tankmates, any fish small enough to fit in its mouth will likely be eaten, ornamental shrimp are not safe companions, and conspecific aggression can be intense, especially in smaller tanks. Selecting tankmates that favour different water layers from the bottom zone can help reduce competition and territorial overlap.

Tire Track Eel Feeding & Diet Considerations

The Tire Track Eel is a predatory species that will readily consume small fish, so nano or bite-sized tankmates should be avoided, will hunt and eat ornamental shrimp, making it unsuitable for shrimp-focused setups, and is primarily active at dusk and dawn, so offering food shortly after lights-off ensures it receives adequate nutrition.

Frequently Asked Questions About Tire Track Eel

How big does Tire Track Eel get?+
Tire Track Eel (Mastacembelus armatus) typically reaches a maximum adult size of approximately 75 cm. They have a eel body shape and a moderate growth rate.
What tank size does Tire Track Eel need?+
A minimum aquarium volume of 680 litres and a tank length of at least 180 cm are recommended for Tire Track Eel. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Tire Track Eel need?+
Tire Track Eel thrives in freshwater only conditions with a temperature range of 22–28°C, a pH between 6.5 and 7.5, and a general hardness of 5–15 dGH. A moderate water flow is preferred.
Is Tire Track Eel peaceful or aggressive?+
Tire Track Eel is classified as semi-aggressive with an aggression score of 6 out of 10. They can work in community setups but may clash with certain tankmates.
Can Tire Track Eel live with others of its kind?+
No. Only one Tire Track Eel should be kept per tank. Keeping multiples in the same aquarium typically results in aggression and stress.
Is Tire Track Eel safe with shrimp?+
No. Tire Track Eel is known to eat ornamental shrimp and is not recommended for shrimp tanks. Even larger shrimp species like Amano Shrimp may be at risk.
Does Tire Track Eel have any special tank requirements?+
Yes. Tire Track Eel benefits from sand (sifters), smooth gravel (sensitive barbels), and driftwood (digestion/hiding) in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.
Does Tire Track Eel need a lid on the tank?+
Yes. Tire Track Eel is a known jumper, and a tight-fitting lid or cover is essential to prevent escape. Even a small gap can be enough for a determined fish to leap out.

Similar Species

Fire Eel

Mastacembelus erythrotaenia

Oddballs
90 cm Mostly Peaceful

The Fire Eel is a stunning, large species of spiny eel native to Southeast Asia, known for its brilliant red lateral stripes and highly interactive, 'dog-like' personality with owners. As a true 'monster fish', it requires massive aquariums. A soft sand substrate is absolutely mandatory, as they will burrow and suffer lethal bacterial infections from scratching themselves on gravel. They are notorious escape artists and will eat any fish small enough to fit in their mouths.

Senegal Bichir

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Clown Knifefish

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Red-Tail Catfish

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Striped Raphael Catfish

Platydoras armatulus

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A highly robust, armored catfish native to the Amazon and Orinoco basins. Famous for their ability to produce audible squeaking or grunting sounds when distressed or defending territory. They are nocturnal scavengers that spend most of the day hiding in driftwood or caves. Note: Their rigid pectoral spines can easily become tangled in standard aquarium nets.

Common Pleco

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