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Mastacembelus plagiostomus

Matthes, 1962Formerly Caecomastacembelus plagiostomus

Last revised 2026Edit this page

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Caecomastacembelus plagiostomus
Caecomastacembelus plagiostomusHippocampus-Bildarchiv

Quick factsEdit

Max size
300mm SL12in SL
Aquarium size
120 × 45cm48 × 18in
Temp
23–27°C73–81°F
pH
8.0–9.5
Hardness
8–25dGH

Difficulty4 of 8 measures

Moderate

How the rating is worked out

Space
large tank
Water
needs alkaline water
Temp
needs a steady temperature
Diet
unknown
Temperament
eats smaller fish
Social
unknown
Compatibility
unknown

Other demands

Each of these can raise the rating on its own, whatever the measures above say.

Hardiness
unknown

Mastacembelus plagiostomus is a spiny eel endemic to Lake Tanganyika, found in shallow water over rocky areas around the shoreline. Very rarely seen in the hobby, it suits a Tanganyikan community of species too large to be considered food and is somewhat territorial with conspecifics. It grows to 300 mm SL, and its stiffened dorsal rays call for care when handling it.

Distribution

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It inhabits rocky areas around the shoreline of the lake, usually in shallow water.

Aquarium size

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Standard length
300mm SL12in SL
Aquarium base
120 × 45cm48 × 18in
Volume
~243litres~64US gal

48" x 18" x 18" (120cm x 45cm x 45cm), although the width of the tank is far more important than the height.

Maintenance

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Use piles of rocks to form sheltered areas. It is essential that the tank bottom is covered in sand as the fish spends much of its time burrowed into the substrate. Gravel is not recommended as its sharp edges can damage the eel's skin. There should be no strong currents in the aquarium.

Water conditions

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Temperature
23–27°C73–81°F
pH
8.0–9.5
Hardness
8–25dGH

Temperature: 23 – 27 °C73 – 81 °F

pH: 8.0-9.5

Hardness: 8-25°H

These recommendations come from this profile’s own figures. They contain affiliate links, so we may earn a commission.

In nature, it preys on small fish but aquarium specimens readily accept dead alternatives. Prawn, cockle, mussel, earthworms and bloodworm can all be offered.

Behaviour and compatibility

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It is peaceful with species it cannot fit into its mouth but is not suitable for most freshwater tanks due to its hard, alkaline water requirements. It is best kept in a Tanganyikan community, where it can be combined with any species too large to be considered food. It tends to be somewhat territorial with conspecifics and a large tank is required if more than one is to be kept.

Sexual dimorphism

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Unknown.

Reproduction

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Has been achieved in the aquarium but very few details are available. The eels should be bred in a species tank. Apparently, the eggs are laid in the substrate or on the underside of rocks and are adhesive. The fry are very small and require infusoria as first food. They look like normal fish fry initially, developing the elongated body as they grow. No parental care is exhibited in this species so if you do get a successful brood it is probably a good idea to remove the parents post-spawning.

Notes

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Very rarely seen in the hobby, this species makes an interesting oddball addition to the Tanganyikan community tank. The species in the family Mastacembelidae are known as "spiny" eels because the dorsal rays are stiffened. Care must therefore be exercised when handling them to avoid injuries. Spiny eels also have no swim bladder, an adaptation to their benthic lifestyle..

How the name has changed

  1. Moved from Caecomastacembelus plagiostomus to Mastacembelus plagiostomus.

    2005Mastacembelidae (Teleostei; Synbranchiformes) subfamily division and African generic division: an evaluation

Distribution

Profile completeness19 of 24

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