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Fire Eel
Mastacembelus erythrotaenia
The Fire Eel is a giant Southeast Asian river fish. This massive carnivore requires a tank of at least 1000 liters featuring very fine sand to prevent self-evisceration and large opaque plastic tubes.
Class:Actinopteri
Order:Synbranchiformes
Family:Mastacembelidae
Genus:Mastacembelus
Species:Mastacembelus erythrotaenia
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Water Temperature
24 - 28 °C
pH Value
6 - 7.5
Water type
Freshwater
Adult size
100 cm
Minimum tank volume
>= 500 L
Minimum group
>= 1
GH
5 - 15 dGH
KH
2 - 7 dKH
TDS
95 - 295 ppm
Conductivity
148 - 461 uS/cm
Species description
Geographical Origin and Habitat: Southeast Asia (Thailand, Cambodia, Borneo, Sumatra). Large slow or moderate flowing rivers. Clay and muddy substrates where they bury themselves during droughts.
Taxonomy and Morphology: Fire Eel (Mastacembelus erythrotaenia). Giant Mastacembelid. Thick and muscular, with the classic prominent fleshy rostrum. Can reach 100 cm (39 inches) in length and a build as thick as a man's forearm.
Social Behavior: Despite its mammoth size, it is renowned for unusual intelligence and sociability. After acclimation, it recognizes the owner, lets itself be petted (hand-feeding) and swims like a ribbon in the water.
Coloration and Sexual Dimorphism: Velvety black/anthracite base color. The entire body is longitudinally striated with bright Fire Red/Orange dashes and stripes, while the fins have a bright red margin. The red intensifies in adults.
Care, breeding and tankmates
Aquarium Setup: Final tank no less than 220-250 cm (86-98 inches / min. 1000 Liters / 260 Gallons). Essential very fine sand (not sharp quartz which eviscerates the eel while digging) and gigantic opaque plastic tubes hidden as a permanent den.
Diet and Feeding: Exclusively carnivorous. Adults: whole fish (sardines), shelled prawns, colossal earthworms, mussels and frogs (frozen). Should be fed sparingly (2-3 times a week) as an adult to avoid intestinal blockage or obesity.
Water Quality: Tolerates wide ranges but produces huge waste (Bioload of a freshwater stingray). Over-filtered tanks (Wet-dry or giant Sumps) are a must. Temperature around 26°C (79°F).
Compatibility and Cohabitation: Excellent. Ironically, the "monstrous" Fire Eel is very peaceful. To be kept with Asian Arowanas, Datnioides, and large Barbs (Tinfoil). Will eat any fish that fits in its mouth, but is not quarrelsome or territorial.
Aquarium Breeding: Never documented. Probably linked to migration to monsoon flooded plains, as for other large Asian eels.
Risks and Diseases: Lethal abrasions. The two biggest killers of the Fire Eel in captivity are the use of coarse gravel (which wears down its mucosa to the point of septicemia) and the absence of a weighted lid, leading it to commit suicide on the house floor.
Geographic Origin and Distribution
Southeast Asia (Thailand, Cambodia, Borneo, Sumatra). Large slow or moderate flowing rivers. Clay and muddy substrates where they bury themselves during droughts.
Origin
South and Southeast AsiaEast Asia
Fish profile
- Temperament
- No verified data available
- Diet
- No verified data available
- Life expectancy
- No verified data available
- Adult size
- 100 cm
- Sex ratio
- No verified data available
- Feeding frequency
- No verified data available
- Bioload
- Extreme
- Flow
- No verified data available
- Jump risk
- No verified data available
- Reproduction
- No verified data available
- Compatibility & tankmates
- No verified data available
- Tank level
- No verified data available
The catalog's scalar value is 100 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 100 cm for this species, recorded as total length (TL). The taxonomic record consulted is Mastacembelus erythrotaenia (v25.04); male or unsexed record. These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
The single-adult profile is classified as extreme bioload. The bioload-v2 rubric deterministically assigns this class from the verified maximum length of 100 cm; it is a catalog management category, not a direct measurement of waste output.
Window to the official scientific data of the species
Data synced on: 06/15/2026
Scientific Parameters & Models
- Trophic level
- 2.7 ± 0.27 se
- Resilience
- Low (4.5 - 14 years)
- Phylogenetic uniqueness (PD50)
- 0.5
- Bayesian Length-Weight
- a = 0.00269, b = 2.94
VulnerabilityHigh vulnerability (60 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
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