Taxonomy & naming
Archiaphyosemion guineense was described by Jacques Daget and Jacques Arnoult in 1954, with the type locality in the Dabola area of the upper Niger drainage in Guinea. The authority is presented in parentheses because the species has been reassigned from its original genus since the original description. Eschmeyer's Catalog of Fishes records the valid name as Archiaphyosemion guineense (Daget & Arnoult, 1954), placed within the family Nothobranchiidae — the African killifishes.
The genus Archiaphyosemion was erected to accommodate a group of West African non-annual killifishes that were previously folded into the broad, now-dismembered genus Aphyosemion. Phylogenetic work on nothobranchiid killifishes has confirmed that Archiaphyosemion is not part of the annual-killi clade: its members do not undergo embryonic diapause and are reproductively and ecologically distinct from the seasonal, peat-spawning lineages. The specific epithet guineense is a Latinised adjective meaning 'of Guinea', indicating the region from which the type material was collected.
The genus contains only a small number of species. Meristic counts for A. guineense include dorsal-fin rays 11–15, anal-fin rays 14–18, and lateral-line scales 29–34, consistent with the elongate, relatively slender body plan typical of the group. Multiple collection localities have been documented in the hobby, including populations from Sierra Leone (coded SL 93/37 from Lenghe-Curoh), Lago, and various sites in the Kissidougou, Tinkisso, and Simandou drainages of Guinea.
Morphology
Archiaphyosemion guineense is a slender, moderately compressed killifish reaching approximately 3 in total length according to FishBase. The body plan is elongate and streamlined in the manner of the non-annual West African killifishes, with the posterior fins relatively broad. Males are more intensely coloured than females, displaying the iridescent patterning typical of the genus — typically combinations of red, blue, and green on the body and fins, with the exact expression varying among collection localities.
Females are plainer and more uniformly brown or olive, with reduced fin pigmentation and a somewhat deeper body when gravid. This pattern of male ornamentation and female cryptic colouration is consistent across the genus. The flanks of males may show a reticulated or spotted pattern, and the unpaired fins typically carry coloured margins or rays. Scale size is moderate, and the head is slightly flattened dorsally with a terminal, upturned mouth — a posture that reflects the species' tendency to spawn near the water surface and to feed on surface invertebrates.
Habitat
In nature, Archiaphyosemion guineense inhabits pools and small streams in the savanna and forest-savanna mosaic of the Upper Niger drainage system. Its documented range covers Guinea (upper Niger tributaries including the Dabola region, Tinkisso, Kissidougou, and Simandou river systems), northeastern Sierra Leone, and northern Liberia. These are inland, upland drainages — not coastal lowland swamps — within the Upper Guinea biodiversity hotspot.
The water in these habitats tends toward the soft and slightly acidic end of the spectrum, though FishBase records a pH range of 6.5–7.2 for the species, which is closer to neutral than many of its West African relatives. Water temperatures in the upper Niger savanna zone typically range from 64–73 °F, and the streams are generally well-oxygenated, flowing over sand or leaf litter. The species is benthopelagic in habit, spending time in the lower and mid water column but ascending to spawn near the surface. It is non-migratory.
Because the water bodies it inhabits are permanent or near-permanent rather than ephemeral seasonal pools, A. guineense does not face the annual desiccation cycle that drives the remarkable life history of annual killifishes. Its habitats are, however, subject to seasonal fluctuation in flow and chemistry with the dry-season recession of the upper Niger tributaries.
Feeding
Archiaphyosemion guineense is a micropredator in the wild, feeding primarily on small invertebrates — insect larvae, small crustaceans, worms, and surface insects — consistent with the diet of most small non-annual West African killifishes. The upturned mouth suggests a preference for surface or near-surface prey, and the species likely takes terrestrial insects that fall onto the water film as a significant part of its diet in its native savanna streams.
In the aquarium, the fish accepts live and frozen foods readily: newly hatched brine shrimp, Daphnia, mosquito larvae, and small bloodworm all suit it well. Most individuals can be trained onto high-quality small dried or micro-pellet foods, though live or frozen items should form the bulk of the diet to maintain colour and condition. Because of its small size, food items must be appropriately scaled — large pellets or chunks of food are ignored or cannot be consumed.
Mating
Archiaphyosemion guineense is a non-annual, plant-spawning killifish. Pairs select a spawning site near the surface or among floating vegetation and mops, where the male courts the female with lateral displays that show off his full fin extent and colouration. Spawning occurs in a brief embrace or side-by-side quiver, with one or a small number of eggs deposited per event. Eggs are adhesive and are attached to fine-leaved plants, moss, or synthetic spawning mop fibres.
The spawning process is distributed over days or weeks rather than concentrated into a single event, with a pair returning to their chosen mop or plant patch repeatedly. This extended, low-intensity pattern of egg deposition is characteristic of the mop-spawning non-annual killifishes and contrasts sharply with the concentrated annual approach. Males may be vigorous in their courtship and can occasionally harass females; providing dense cover or multiple visual breaks reduces stress on the female.
Breeding
Eggs of Archiaphyosemion guineense are approximately 0.5 in in diameter and incubate in water without any requirement for diapause or a dry period. At around 70 °F (70 °F) eggs hatch in approximately 8 days; at 76 °F (75 °F) the incubation period shortens to about 13 days, according to records from the American Killifish Association — an inversion of the usual expectation, though both figures fall within a biologically plausible range for water incubation at these temperatures. Hatchlings are large relative to the eggs and are capable of taking newly hatched brine shrimp (Artemia nauplii) as a first food immediately after the yolk sac is absorbed.
Growth is reported as rapid under good conditions, with sexing becoming possible at around six months of age. The eggs are typically collected by removing and replacing mops at intervals of one to two weeks, or by keeping parents over a bare-bottom tank and moving them periodically. Eggs can be incubated in shallow containers of clean water from the breeding tank, maintained at the appropriate temperature and monitored for fungus. Infertile eggs should be removed promptly. Because the species is non-annual, fry rearing is comparatively straightforward compared to annual species requiring peat incubation and variable diapause periods.
In the aquarium
Archiaphyosemion guineense is kept primarily by killifish enthusiasts rather than in the general trade. It is a peaceful small fish well suited to a species tank or a carefully chosen community with other small, non-aggressive fish that share similar water requirements. A well-planted aquarium of 10–15 US gal, with a tight-fitting lid — essential for all killies, which are capable jumpers — and floating plants or surface cover provides appropriate conditions.
Water should be soft to moderately hard and slightly acidic to neutral: targeting pH 6.5–7.0 and temperatures of 68–73 °F aligns with its natural range in the upper Niger highlands. The species appreciates well-oxygenated water and does not tolerate stagnant or heavily polluted conditions. A dark substrate and background help display male colouration to best effect. Regular small water changes are more beneficial than infrequent large ones, maintaining water quality without large swings in chemistry or temperature.
In the hobby, individuals are typically sourced through killifish society exchanges, where locality data is tracked carefully. The American Killifish Association maintains records of collected strains and their origin codes, making it possible for breeders to maintain geographically meaningful lines. Like many killifish, A. guineense is not a long-lived fish in the aquarium by general standards, but the ease of breeding means that maintaining a colony across generations is well within reach for attentive keepers.
Conservation
The IUCN Red List assessed Archiaphyosemion guineense as Least Concern on 2 January 2020. The species' range across the upper Niger tributaries of Guinea, Sierra Leone, and northern Liberia encompasses several river systems, which provides some resilience against localised disturbance, and no specific population collapse has been documented.
Nevertheless, the Upper Guinea region faces significant and accelerating pressures. Deforestation in the West African forest-savanna mosaic has accelerated throughout the species' range, degrading the riparian cover and leaf-litter input that characterise the small streams it inhabits. Agricultural expansion, mining activity in Guinea's interior — particularly bauxite and iron ore extraction in areas that overlap with the species' range — and associated runoff and sedimentation pose ongoing threats to water quality in its savanna-stream habitats. Climate projections for the West African Sahel and Guinea highlands suggest increased dry-season intensity and reduced stream flows, which would compress the permanent water habitats on which this non-annual species depends.
The species is not heavily collected for the ornamental trade, and its presence in killifish hobbyist networks means that captive-bred populations exist outside its native range. These provide some insurance against local extirpation, though they are not a substitute for in-situ habitat conservation. Periodic reassessment of its status as land-use change continues across Guinea and Sierra Leone would be prudent.