Mastacembellus greshoffi

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Mastacembellus greshoffi is an African spiny eel from the Congo River basin, mainly associated with the Democratic Republic of the Congo. Its elongated body, tubular snout, and extended dorsal and anal fins give it a distinctive appearance. This bottom-dwelling fish is secretive and often shelters in the substrate or among aquarium décor, becoming more active as light levels fall. Uncommon in the aquarium trade without being completely unavailable, it should be kept by aquarists able to provide a spacious, stable, tightly covered aquarium. The specimens offered here are wild collected, and this species is available exclusively from Ton.Fish in Canada.

General species description

Mastacembellus greshoffi belongs to the African spiny eels, a group of fishes without pelvic fins and with a series of flexible spines at the front of the dorsal fin. Its lifestyle is mainly benthic: it explores the bottom with its elongated snout and may partially bury itself in suitable substrate. It is generally secretive during the day and more active at dusk and night. Care requires patience, since newly imported individuals may remain hidden during acclimation. This is an uncommon species in the trade, and its adult size means that the aquarium should be both long, spacious, and tightly covered.

Geographic origin and habitat

The species is associated with the Congo River basin, particularly in the Democratic Republic of the Congo. It inhabits bottom areas of rivers and quieter or moderately flowing sections where roots, stones, leaf litter, and soft deposits provide shelter. In this type of habitat, light is often filtered by riparian vegetation and organic matter. In an aquarium, a layout with tubes, roots, and cavities better suits its habits than a very open tank. Effective filtration, well-oxygenated water, and moderate flow are beneficial, without turning the aquarium into a torrent. A soft bottom with abundant cover is especially important for reducing stress.

Precise location and local name

The general range assigned to Mastacembellus greshoffi is the Democratic Republic of the Congo, within the Congo River drainage. The most useful common name in the aquarium trade is African spiny eel, a descriptive name shared by several related species. The name spiny eel is also widely used in English-language trade. These names do not replace scientific identification, since several African spiny eels may look similar when young. For wild fish, it is best to retain the collection information supplied by the importer and avoid mixing populations whose detailed origin is not known. The Congo basin remains the main geographic reference for this species.

Appearance and physical characteristics

The body of Mastacembellus greshoffi is very elongated, laterally compressed toward the rear, and covered with small scales. Its tubular snout and mouth are adapted for searching through the bottom. The dorsal fin begins behind the head and extends along much of the back, while the anal fin has a similar extension beneath the body; both are joined at the base of the caudal fin. Overall coloration is dark, ranging from brownish to grayish, with patterns that may vary with age and population. As with several spiny eels, the first dorsal spines should be handled carefully. Its snake-like profile and mobile snout are its most immediately recognizable features.

General diet

In the wild, Mastacembellus greshoffi mainly feeds on small bottom-dwelling prey located with its sense of smell and elongated snout, including worms, insect larvae, small crustaceans, and other invertebrates. Wild fish may initially refuse dry food, especially after transport. Begin with sinking, strongly scented foods such as bloodworms, pieces of shrimp, clean earthworms, or frozen foods intended for carnivorous fish. Once acclimated, it may learn to accept quality meaty pellets, although these should not be the only food offered. Feed when the aquarium lights are dimmed or off. Its nocturnal hunting behavior and carnivorous invertebrate-based diet should guide the selection of tank mates.

Essential data

• River of origin: Congo River basin
• Local name used: African spiny eel
• Origin of the scientific name: Mastacembelus is the genus name; greshoffi is a specific name dedicated to Greshoff
• Full-name etymology: Mastacembelus comes from Greek and refers to an elongated mouth or snout; greshoffi honors a person named Greshoff
• Common or vernacular names: African spiny eel; spiny eel
• Family: Mastacembelidae
• Subfamily: Mastacembelinae
• Name pronunciation: mas-tass-EM-beh-luss - gre-SHOF-ee
• Discovery: George Albert Boulenger, 1892
• Maximum adult size: up to about 60 cm
• Water temperature and pH: 24 to 28 °C; pH 6.0 to 7.5
• Watercourse appearance and surrounding vegetation: shaded sections with roots, leaves, and stones, bordered by riparian vegetation
• Typical tank mates: Phenacogrammus interruptus, Synodontis schoutedeni, Steatocranus casuarius, Raiamas christyi, Ctenopoma acutirostre
• Temperament and behavior: secretive, mainly nocturnal, and peaceful toward fish too large to swallow
• Water depth: bottom areas and sheltered sections of waterways
• Sexual dimorphism: difficult to identify visually; mature females may be more robust-bodied
• Bottom configuration and flow: soft substrate, roots, and plant debris; low to moderate flow

In your aquarium

Success with Mastacembellus greshoffi depends on a mature, spacious aquarium with a secure lid and no escape gaps, since spiny eels are excellent escape artists. Provide soft substrate, several shelters, and subdued lighting. Slow acclimation is especially useful for a wild fish. Offer small meaty meals after the lights go out and remove leftovers to protect water quality. Avoid tank mates small enough to be swallowed. Stable water, strong biological filtration, and regular water changes are essential for keeping this secretive animal in good condition.