Taxonomy & naming
Micropanchax ehrichi was described by Berkenkamp and Etzel in 1994, with type localities recorded as a slow-flowing creek near Samalofila, southwest of Bamako, and a second locality east of Bougouni — both in southwestern Mali. The authority is presented in parentheses in the conventional format (Berkenkamp & Etzel, 1994), indicating the name has been moved or was first established in a combination other than the one currently in use. Eschmeyer's Catalog of Fishes is the governing authority for the valid name.
The species belongs to the genus Micropanchax, a grouping of small lampeye killifishes distributed across sub-Saharan Africa and the upper Nile drainage. Lampeyes — sometimes treated within Aplocheilichthyinae — are characterised by a reflective, light-organ patch of iridophores above and around the eye that produces the blue-green iris shimmer for which the group is named. Micropanchax encompasses several West African species whose ranges overlap in the Sahel-savanna transition zone and the upper tributaries of the Niger.
No subspecies or recognised geographic variants have been described for this species. Its relationship to other Micropanchax species in the Niger basin awaits a modern molecular phylogenetic treatment of the genus.
Morphology
Ehrich's lampeye is a slender, fusiform fish with a maximum recorded total length of 1.5 in (FishBase). The body is elongate and laterally compressed, with the dorsal profile slightly more arched than the ventral. The dorsal fin carries 5–7 rays and the anal fin 11–14 rays; both counts are consistent with other small-bodied West African lampeyes.
Colouration is pale olive-grey with a light blue iridescence on the flanks; the ventral area is white, and individual scales are margined with darker pigment, giving the body a faintly reticulated pattern in good light. The unpaired fins are pale green. Most distinctively, both sexes display the iridescent blue-green iris reflection — the characteristic lampeye light-organ — which catches light and serves as an intraspecific signal. Sexual dimorphism is low; males and females are broadly similar in colour and fin shape, though females may be slightly fuller-bodied when gravid.
Habitat
The species is known from the upper Niger drainage in southwestern Mali, at localities near Bamako and east of Bougouni. Both type localities are described as slow-flowing creeks — the shallow, vegetated, often sluggish tributaries and marginal waters characteristic of the Sudan-savanna zone, where seasonal rainfall dictates water levels but the creeks themselves persist year-round. These are permanent-water environments; the species is not adapted to the drying seasonal pools that support annual killifishes elsewhere in West Africa.
FishBase classifies it as benthopelagic and non-migratory, found most commonly schooling in the upper water layers of its creek habitat. Water chemistry for the upper Niger in the Bamako region is typically soft to moderately hard and near-neutral to slightly alkaline, reflecting the geology of the basement rocks and the influence of the dry Sahel climate on river mineralisation. The species shares its habitat with other small schooling fishes of the open-water and margin zones of these creeks.
Feeding
Like other small lampeye killifishes, Micropanchax ehrichi is primarily an insectivore and micro-predator. Its compact, upturned mouth and mid-water schooling habit are well suited to taking small aquatic and surface-fallen invertebrates — chironomid larvae, small crustaceans, zooplankton, and emergent insects. FishBase records it as a tropical freshwater species with a benthopelagic foraging range, consistent with feeding across the water column from the surface film to the lower midwater.
In the aquarium, Ehrich's lampeye accepts live and frozen micro-foods readily: Artemia nauplii, micro-worms, Daphnia, and finely minced or powdered dried foods. Because of its small adult size, food particle dimensions matter; adult-sized pellets are not appropriate. Offering a varied diet that includes live or frozen invertebrates maintains condition and supports colour development, particularly the brilliance of the iridescent eye patch.
Mating
Ehrich's lampeye is a non-annual, continuous spawner — a reproductive strategy fundamentally different from the diapausing annual killifishes of seasonal pools. It inhabits permanent water and does not produce eggs capable of surviving substrate desiccation. Instead, pairs and small groups spawn repeatedly over extended periods, with individual females depositing only a few adhesive eggs at each act, spread across multiple sessions rather than in a single mass clutch.
Mating in lampeyes occurs in the mid-water and near plant surfaces. The male courts the female with display behaviour that highlights the iridescent eye patch; the breeding drive is persistent and not confined to a seasonal trigger. After a brief pairing the female deposits adhesive eggs onto fine-leaved plant material, moss, spawning mops, or root surfaces. The eggs are small, transparent, and sticky, adhering by a short filament or surface texture to whatever substrate the female selects.
Breeding
Eggs are deposited individually or in very small batches over days and weeks. Each egg adheres to its substrate and develops independently; there is no nest, no guard, and no parental care of any kind. Incubation takes approximately 10–14 days at warm tropical temperatures (75–82 °F), after which the larvae hatch as tiny, free-swimming fry capable of feeding on infusoria-sized prey almost immediately.
In the aquarium, breeding is readily achieved by furnishing the tank with fine-leaved plants (Java moss, Ceratophyllum, or synthetic spawning mops) and allowing a small group of adults to spawn at will. Eggs can be removed daily by inspecting and rinsing the mop or plant clump into a shallow rearing container, then incubated separately to protect them from adult predation. Fry are very small at hatching and require micro-sized first foods — infusoria, green water, or commercial fry powder — before graduating to Artemia nauplii at around one week of age. Growth to sexual maturity takes approximately two to three months under good conditions.
In the aquarium
FishBase describes Micropanchax ehrichi as easy to maintain in the aquarium, and the species is well suited to a small, planted species tank or a peaceful community of comparably sized West African fishes. A group of six or more is recommended; lampeyes are schooling fish and display best and show the least stress-related pallor when kept in numbers. The iridescent eye patch, which is the principal ornamental feature, shows most brilliantly in a shaded tank with a dark substrate and gentle, diffused lighting.
Water conditions should reflect the soft-to-moderate, near-neutral chemistry of the upper Niger drainage: temperature 72–79 °F, pH 6.5–7.5, and low to moderate hardness. Filtration should provide gentle flow; lampeyes are not strong swimmers and prefer calm surface water. Dense planting along the sides and back of the tank, with open midwater swimming space, replicates the creek-margin habitat. The species poses no threat to any fish too large to swallow whole, but its own small size makes it vulnerable to larger or aggressive tankmates.
Conservation
The IUCN Red List assessed Micropanchax ehrichi as Least Concern (LC) in 2019 (assessors: Aboubacar Awaïss and Philippe Lalèyè). The assessment reflects a distribution spanning multiple localities in the upper Niger drainage of southwestern Mali, a range broad enough to preclude the most acute single-site extinction risk scenarios. Nevertheless, the assessment date (2019) predates more recent documentation of environmental pressures in the Bamako region, where rapid urban expansion, agricultural water abstraction, and degradation of small stream habitats have accelerated.
Slow-flowing creeks in the Sudan-savanna zone are sensitive to land-use change: deforestation of riparian margins reduces shading and silt retention, agricultural run-off elevates turbidity and nutrient loads, and water extraction for irrigation can reduce or eliminate low-gradient creek flow in the dry season. A species dependent on permanent-water habitats and restricted to the upper Niger basin is thus exposed to cumulative pressures that could narrow its range without triggering a formal reassessment in the near term. Monitoring of the creek habitats around Bamako and Bougouni is warranted.