Taxonomy & naming
Bryconalestes derhami was described by Jacques Géry and Volker Mahnert in 1977. The species is placed in the genus Bryconalestes, a West African alestid genus whose members were historically shuffled between several genus-level concepts before the current arrangement stabilised. Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) records the valid name as Bryconalestes derhami (Géry & Mahnert, 1977), with the parenthetical authority indicating the species was not originally described under its current genus name. The family Alestidae encompasses the African tetras — a diverse radiation of characiform fishes distributed across sub-Saharan Africa, distinct from the superficially similar American characids.
Diagnostic characters of B. derhami include the presence of a parietal fontanella in adults, a precaudal spot that is ovoid in shape, 26 to 30 lateral line scales, and an anal fin carrying 22 to 24 soft rays. These counts and the fontanella character help separate it from its congeners within the often confusing West African alestid assemblage.
Morphology
Bryconalestes derhami is a small alestid reaching a maximum recorded standard length of 3 in. Like other members of the genus it is slender and laterally compressed, with the streamlined fusiform body plan typical of pelagic-zone characiforms that exploit fast-moving water or open midwater in rivers.
The body carries spotted pigmentation, and the fin formula includes a dorsal fin with approximately 10 rays and an anal fin with 22 to 24 rays — the relatively long anal fin is a Bryconalestes characteristic. An ovoid precaudal spot is present, and the parietal fontanella — an opening in the skull roof — persists into adulthood, a feature that distinguishes this species from some congeners in which the fontanella closes during development. Detailed colour information from living specimens is sparse in the available literature.
Habitat
Bryconalestes derhami is distributed in the river systems of southwestern Côte d'Ivoire and Liberia, within the Upper Guinean forest region — one of Africa's globally significant biodiversity hotspots and an area of severe ongoing habitat loss. It is recorded as a freshwater pelagic species, occupying the open water column rather than tight benthic or marginal-vegetation zones, in tropical lowland rivers.
Detailed habitat documentation for this species in the primary literature is limited. The closely related and better-studied B. longipinnis inhabits both upper and lower river courses, preferring soft, slightly acidic water (GH 2–5, pH around 6.0–6.5, temperature 75–79 °F) — conditions that probably approximate the biotope B. derhami occupies in the forest rivers of Côte d'Ivoire and Liberia, where the lateritic catchments typically yield soft, warm, mildly acidic water.
Feeding
No published dietary study specific to Bryconalestes derhami is available. As a pelagic alestid in tropical West African rivers, it almost certainly feeds opportunistically on invertebrates, insect larvae, and small prey items taken in the water column — the feeding mode typical of Bryconalestes and related alestid genera.
In a care context, related West African tetras of similar size accept small live and frozen foods (Daphnia, Artemia nauplii, bloodworm) and adapts to quality dry foods. A varied diet is preferable to reliance on a single food type.
Mating
No specific observations of courtship behaviour in Bryconalestes derhami have been published. Alestids generally are egg-scattering open spawners; male display is likely visual, with fish patrolling or pursuing females through open water or near fine-leaved vegetation. The genus does not exhibit mate guarding or nest construction.
In well-maintained aquaria, related Bryconalestes species are understood to spawn in groups, with males chasing females until eggs and sperm are released in open water or near plant cover. Courtship and spawning intensity typically increases with improving condition and seasonal temperature cues.
Breeding
Bryconalestes derhami has not been documented in captive breeding in the accessible literature, and the species is essentially absent from the hobby. Extrapolating from the alestid life-history model, it is an egg-scattering spawner producing adhesive or semi-adhesive eggs among fine-leaved plants, with no parental care; adults would be expected to consume eggs if not separated.
Should captive material become available, the approach used for other small West African tetras — a warm, softwater, well-planted spawning tank, removal of adults after spawning, and very small first foods for fry — would be the logical starting point. At present the conservation status of the species makes any aquarium work with it inherently of interest for ex-situ management.
In the aquarium
Bryconalestes derhami is not an established aquarium fish. It does not appear in the trade under any recognised common name, and there are no published husbandry accounts. Any specimens that might reach specialist keepers should be treated as delicate West African forest-river fish, maintained in soft, warm, slightly acidic water similar to the conditions documented for B. longipinnis (pH 6.0–6.5, 75–79 °F, low hardness) and fed on a variety of small live and frozen invertebrate foods.
Given its Endangered status, its restricted natural range, and the absence of any established captive population, the species is unlikely to become a hobbyist fish in the near term. Interest in it from a conservation or scientific standpoint would be more meaningful than its pursuit as an ornamental species.
Conservation
Bryconalestes derhami is assessed as Endangered (EN) on the IUCN Red List under criterion B2ab(iii), assessed on 6 May 2019. The B2 criterion flags a restricted area of occupancy combined with continuing decline in habitat quality — here, the ongoing destruction of the Upper Guinean forest zone in Côte d'Ivoire and Liberia, which has been subjected to some of the highest deforestation rates recorded for any tropical forest region in Africa. River systems embedded in that landscape lose riparian shade, experience increased sedimentation and run-off, and are subject to pollution from agriculture and artisanal mining.
The species' range is naturally limited to southwestern Côte d'Ivoire and Liberia — a coastal-forest river arc with no deep geographic buffering. There is no record of the species in ex-situ conservation programmes, and its low profile in the aquarium trade means it cannot rely on the hobbyist breeding networks that support some other Endangered West African fishes. Formal field surveys to establish current population status and precise distributional limits would be a necessary first step toward any targeted conservation action.