Taxonomy & naming
Scriptaphyosemion nigrifluvi was described by Romand in 1982, with the type locality recorded at Mamou in central Guinea, within the Fouta Djallon highlands. The original description placed the species in Aphyosemion — the catch-all genus for many West African killifishes at the time — and the name Roloffia nigrifluvi was also in currency during the period of taxonomic flux that preceded modern molecular work. Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) records the current valid combination as Scriptaphyosemion nigrifluvi (Romand, 1982), with the authority in parentheses indicating the generic reassignment.
The genus Scriptaphyosemion, erected by Radda & Pürzl in 1987, unites a cluster of small, non-annual West African killifishes from the Upper Guinean forest zone of Guinea, Sierra Leone, Liberia, and Côte d'Ivoire. The killi-data.org name resolver confirms the synonymy: Aphyosemion nigrifluvi and Roloffia nigrifluvi are deprecated names, both now subsumed under the valid Scriptaphyosemion combination. The genus name combines the Latin scripta ('written' or 'marked') with the older genus name Aphyosemion (from the Greek aphyē, small fish, and sēmeion, mark or sign), together evoking the elaborate markings that distinguish the males of these species from one another.
The specific epithet nigrifluvi is a Latin compound from nigri- ('black') and fluvi ('river'), a direct reference to the Bafing River — the upper-basin drainage that defines the species' type locality — whose local name means 'black river', reflecting the dark, tannin-rich colour of its waters.
Morphology
Scriptaphyosemion nigrifluvi is a small, slender killifish reaching approximately 2 in total length, as recorded by FishBase; the Killi-Data encyclopedia notes a maximum approaching 3 in, though the majority of individuals encountered in hobby collections are at the smaller end of that range. The body plan is typical of the genus: moderately laterally compressed, with a slightly upturned mouth suited to surface-oriented feeding, and the dorsal fin set well back toward the caudal peduncle.
Sexual dichromatism is pronounced, as is characteristic of Scriptaphyosemion. Males display a reticulate pattern of spots and streaks — typically in red-orange to reddish-violet tones — overlaid on a greenish-blue or olive-grey body ground colour, with the dorsal, caudal, and anal fins extending and elaborating this colouration. Females are cryptically coloured in plain olive or yellowish-brown, with minimal fin patterning and a rounded caudal fin. The extent and vividness of male colouration vary with condition, dominance, and water quality.
Habitat
The species is known from the upper Bafing River basin in the Fouta Djallon region of Guinea, a highland plateau that forms the headwater divide for several major West African river systems. Collection records compiled in the Killi-Data encyclopedia place the species at Mamou, Ngabu, Kenema, and Magbenta — localities spanning Guinea and the adjacent Sierra Leone border zone — within a landscape of savanna-forest mosaic and gallery forest streams draining laterite and granitic substrates.
FishBase describes the habitat as quiet brooks, swamps, and weedy parts of small streams: slow-moving, plant-fringed, shallow water typical of the Guinean headwater zone. The water in such streams is characteristically soft, low in dissolved salts, slightly to moderately acidic, and lightly stained with tannins from decaying leaf litter and riparian vegetation. As a non-annual species, S. nigrifluvi inhabits permanent or near-permanent water bodies that retain flow through the dry season rather than the ephemeral pools that annual killifishes depend upon. The highland elevation of the Fouta Djallon imparts a somewhat cooler thermal regime than the lowland coastal forests occupied by some congeners.
Feeding
Scriptaphyosemion nigrifluvi is a micro-predator in the wild, subsisting on the small aquatic invertebrates, insect larvae, microcrustaceans, and surface-fallen insects that colonise the margins and water surface of its forest and savanna-edge streams. The upward-directed mouth is well suited to taking items from or near the surface film, and feeding behaviour in the genus generally reflects this orientation.
In the aquarium the species accepts live and frozen invertebrate foods readily: Daphnia, Cyclops, bloodworm (Chironomus larvae), and Artemia nauplii are all suitable and help maintain colour in males. Small, appropriately sized dried foods may be accepted by settled fish, but a diet based substantially on live or frozen prey is advisable for this genus. Feeding twice daily in modest amounts prevents overfeeding and maintains water quality in the small, lightly filtered aquaria typical of killifish keeping.
Mating
Scriptaphyosemion nigrifluvi is a non-annual, plant-spawning killifish — the Killi-Data encyclopedia records it under the B3 (plant/mop spawner) breeding category. Unlike annual killifishes that bury their eggs in substrate and rely on diapausing eggs to survive dry seasons, S. nigrifluvi inhabits permanent streams and deposits adhesive eggs on fine-leaved aquatic plants, submerged roots, or floating spawning mops, where the eggs develop continuously in water without any diapause phase.
Spawning is pair-based and extended over time. A conditioned male courts a receptive female with lateral displays that showcase his flank and fin patterning; when both fish are aligned among plant material, the pair deposit one or a small number of adhesive eggs per spawning embrace. This process is repeated across multiple sessions over days or weeks. The adhesive eggs cling to plant leaves or mop fibres and are not subject to the handling requirements — dry peat, cool storage — that characterise annual killi eggs.
Breeding
Breeding in the aquarium is achieved by conditioning a pair or a small group — one male with two or more females — on live and frozen foods in a small, densely planted tank. Water parameters should reflect the natural chemistry of Fouta Djallon highland streams: soft (low total hardness), slightly acidic (pH approximately 6.0–6.8), with temperatures in the range of 72–77 °F consistent with the highland provenance of this species. Fine-leaved plants such as Java moss or commercial nylon spawning mops serve as egg-deposition sites.
Eggs are collected every few days by removing the mop or plant material to a shallow hatching container of similar water. Unlike annual killi eggs, S. nigrifluvi eggs should not be dried or stored in peat — they incubate directly in water and typically hatch within two to three weeks at the temperatures noted. Fry are small at hatching and require appropriately fine first foods: infusoria, micro-worms, or newly hatched Artemia nauplii. Adults are comparatively long-lived relative to annual killifishes and do not die after a single spawning season, making them a manageable entry point for hobbyists new to West African killifish.
In the aquarium
Scriptaphyosemion nigrifluvi circulates primarily within specialised killifish societies and hobbyist networks rather than the general ornamental trade; it is not a commonly encountered species in fish shops. A small aquarium of 10–15 US gal suits a pair or trio well. Dense planting with fine-leaved species — Java moss, water sprite, or Ceratopteris — provides both the cover males use during courtship and the surfaces on which eggs are deposited. Floating plants or surface coverage help diffuse light and approximate the shaded, tannin-tinted environment of natural highland streams.
Water should be soft and slightly acidic, maintained with regular small partial changes. The tight-fitting lid non-negotiable for all killifishes — S. nigrifluvi, like its congeners, is an accomplished jumper. Males should not be housed together in small aquaria as aggression between them is typical; a single male with two or more females is the recommended social arrangement. The species is best kept in a species aquarium or with small, peaceful fishes sharing similar water-chemistry requirements. Its quiet disposition and the male's vivid Scriptaphyosemion colouration make it a rewarding species for the specialist hobbyist.
Conservation
The IUCN Red List assessed Scriptaphyosemion nigrifluvi as Vulnerable (VU) in 2020, under criteria B1ab(iii)+2ab(iii) — the criterion set that flags a species as having both a restricted extent of occurrence (B1) and a restricted area of occupancy (B2), with ongoing decline in habitat quality (iii). The IUCN taxon record (ID 169460, assessment ID 58324013) notes the species' limited known range within the upper Bafing basin and the adjacent Guinea–Sierra Leone border zone.
The Fouta Djallon highlands, while less severely deforested than the lowland coastal forests of Sierra Leone and Liberia, nonetheless face substantial and accelerating pressure. Agricultural expansion — driven by population growth and the conversion of gallery forest and savanna-margin streams to rice paddies and market gardens — degrades the riparian cover and water chemistry on which species like S. nigrifluvi depend. Artisanal mining activities, widespread across Guinea's interior, introduce siltation and chemical contamination into small highland streams. The species' restricted range and its dependence on clear, stable, well-shaded water make it inherently vulnerable to these pressures: a non-annual killi has no diapausing egg bank to bridge population crashes, so local extinction of a stream population is effectively permanent. Captive propagation within killifish hobby networks represents the primary insurance against global loss should wild populations decline further.