Taxonomy & naming
Aphyosemion labarrei was described by the Belgian ichthyologist Max Poll in 1951 from 73 specimens collected by Clément Labarre the previous year near the village of Kiavo, approximately 12 mi from Madimba in what was then the Belgian Congo (now the Democratic Republic of the Congo). The type locality lies in the Inkisi River drainage, a tributary of the lower Congo.
Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) treats Aphyosemion labarrei Poll, 1951 as the valid name. The species has been placed in the subgenus Mesoaphyosemion on the basis of morphology and colour-pattern characters shared with other members of that group. The synonym Aphyosemion brichardi is listed in the hobby literature and on AKA records; poll also described brichardi from the same broad region, and these names have been treated as synonymous. Killifish systematists continue to refine the boundaries of species groups within Aphyosemion using molecular methods, and the placement of labarrei may be subject to further revision.
The species is tracked by the American Killifish Association under collection codes including Ngeng AVD 2011, Kingambe AVD 2011, and several Zaire-era localities (Kisantu, Madimba, Mai-Ndombi, Mbanza-Ngungu, Nenga AVD 2011), reflecting the multiple collection points documented across the Inkisi system.
Morphology
Aphyosemion labarrei is a slender, laterally compressed killifish reaching approximately 2 in total length; FishBase gives a maximum of 2 in TL and the WAK reference records 2 in. The body proportions are typical for the genus: a slightly pointed snout, an upturned mouth suited for surface feeding, and a rounded caudal fin that in males carries the species' most striking ornament.
Male colouration is the defining character: the flanks display a strong blue metallic iridescence, and the outer margins of the caudal fin are very broadly edged in red — a combination that makes labarrei visually distinctive among the forest killies of central DRC. Dorsal, caudal, and anal fins may carry additional red-orange spotting or patterning on the blue-green ground colour typical of the subgenus. Females are cryptically coloured, as in the majority of Aphyosemion species: brownish or olive above, paler below, with reduced finnage and little of the male's iridescence. Sexual dimorphism is pronounced; sexing adults is straightforward.
Meristic counts from the WAK reference place dorsal fin rays at 12–14 and anal fin rays at 14–17. Eggs are notably large for a killifish of this size, measuring 0.5 in in diameter.
Habitat
In the wild, Aphyosemion labarrei inhabits the small rainforest brooks, stream headwaters, and swampy marginal areas of the Inkisi River drainage and the Ngufu tributary in the lower to middle Congo basin of western DRC. FishBase characterises the microhabitat as small brooks and small streams within the rainforest — typically shallow, heavily shaded by riparian vegetation, with soft, acidic water stained by leaf litter and decaying organic matter.
The species is benthopelagic and non-migratory, living in or near permanent water year-round. Unlike annual killies that exploit temporary rain pools and bury desiccation-resistant eggs in substrate before their home waters dry out, A. labarrei lives in stable or near-stable stream environments where water persists through the dry season. Temperature in nature is characterised as tropical, with FishBase recording a range of 72–75 °F. The WAK reference notes that the species can breed at temperatures as low as 57 °F (58 °F), suggesting some capacity to handle cooler conditions than its tropical range might imply.
Multiple collection sites across the Inkisi system — including localities gathered in the AVD 2011 expedition (Ngeng, Kingambe, Nenga) and older Zaire-era records — indicate the species occupies a range of stream and swampy habitats across the drainage rather than being confined to a single site, though the overall range remains restricted by the limits of the Inkisi system in western DRC.
Feeding
Aphyosemion labarrei is a micro-predator in the wild, taking small invertebrates — aquatic insects and their larvae, small crustaceans, and other zooplankton-sized prey — as typical for rainforest stream Aphyosemion. The upturned mouth is well adapted for intercepting invertebrates at and just below the water surface, and small terrestrial insects that fall onto the stream surface are taken opportunistically.
In the aquarium the species is straightforward to feed. Live foods are ideal and promote the best colouration in males: Drosophila (fruit flies), micro worms, bloodworm, Artemia nauplii, and small live Daphnia all work well. Frozen equivalents of the same prey items are accepted by settled specimens. High-quality micro-pellets or crushed flake can serve as a supplement but should not be the sole diet if condition and colour are priorities. Small, frequent feedings suit the species' natural feeding style better than one large daily meal.
Mating
Aphyosemion labarrei is a non-annual, plant-spawning killifish. Unlike the annual species of open savanna and seasonal pools that bury eggs in substrate to survive dry-season drought, labarrei spawns over days and weeks into fine-leaved plants, spawning mops, or roots near the surface or substrate, and the eggs develop directly in water with no diapause.
The WAK reference notes that males can be aggressive toward one another and toward females; a ratio of one male to two or three females is recommended to spread male attention and reduce injury to individual females. Males display actively, fanning their fins and intensifying the blue and red colouration to court females. The pairing is not permanent — like most Aphyosemion the species is polygamous in practice, with a single male spawning with multiple females across a season. Courtship in the aquarium is typically quiet and persistent rather than explosive, with pairs or small groups working through a planted or mop-equipped tank over several weeks.
Breeding
Spawning occurs at or near the substrate or among plants and spawning mops; the eggs are adhesive and relatively large at 0.5 in diameter. In water at the recommended breeding temperature of 68–73 °F (68–74 °F), eggs hatch in approximately 12–14 days, though the WAK reference records a range of 9–18 days depending on temperature and conditions. This direct water-incubation approach — no peat, no dry storage, no diapause — is characteristic of the non-annual Aphyosemion.
Fry emerge at 0.5 in and initially require infusoria or similarly fine first foods before graduating to Artemia nauplii and micro worms within the first week. Growth is described as fairly rapid initially before slowing; sexual maturity is reached at approximately five months. The WAK reference characterises labarrei as a species that is reportedly difficult to breed, though Jorgen Scheel found it straightforward to keep and breed under appropriate conditions — the difficulty appears to stem from meeting the soft-water requirement and maintaining appropriate temperature rather than from any inherent breeding complexity.
A water hardness as soft as DH 15 has been recorded in successful breeding attempts. Separating eggs or fry from adults is advisable, as the adults will eat them; either removing mop or plant clumps to a separate rearing vessel, or moving the adults after a spawning period, are standard approaches. Not a long-lived species; individuals likely live one to two years under aquarium conditions.
In the aquarium
Aphyosemion labarrei is suitable for experienced killifish keepers rather than beginners. It is a small, peaceful fish with conspecifics of appropriate size, but the requirements for soft, slightly acidic water at moderate temperatures, and the care needed in feeding and breeding management, place it in the intermediate-to-advanced category. It has been held in the hobby since the early 1970s (first imported to the Netherlands and UK, and given the NSC-4 code in North America), and there is a documented hobbyist literature spanning 25 or more articles in the Journal of the American Killifish Association.
A small species tank — a 10–15 US gal aquarium with a tight-fitting lid to prevent the surface-oriented fish from jumping — is appropriate for a pair or small group. Soft, slightly acidic water (pH 6.0–6.8, hardness below 10 dH) with gentle filtration and regular partial water changes suits the species well. Temperature should be maintained in the 68–75 °F range; the WAK reference notes spawning activity even at 57 °F, but warmer conditions in the 72–75 °F range are typical for maintenance. Dense planting or spawning mops provide both cover and spawning sites; low or moderate lighting keeps the fish at ease.
Males are best kept one per tank or with ample females present to diffuse aggression. The species is a good choice for a species-only setup or a carefully managed killifish community. Its striking male colouration — the metallic blue body and red-margined caudal fin — rewards the effort of maintaining correct conditions.
Conservation
The IUCN Red List assessed Aphyosemion labarrei as Least Concern (LC) in February 2009. The assessment reflects a species that, while restricted to the Inkisi River drainage in western DRC, occurs at multiple localities across that system and inhabits permanent streams rather than the ephemeral pools that make annual killies acutely vulnerable to seasonal water loss.
Nonetheless, the broader context for small-stream rainforest killies in the Congo basin gives cause for watchfulness. Deforestation in the lower Congo region reduces the riparian shade and leaf-litter input that maintain the cool, soft, acidic conditions these fish depend on; sedimentation from agriculture and land clearing degrades stream habitats; and the introduction of exotic species — including the widely released mosquitofish Gambusia affinis, used for malaria-vector control across tropical Africa — poses a demonstrated threat to small endemic killies wherever it is established. The political instability of the DRC has also historically limited the frequency of field surveys, meaning that population trends for species like labarrei are poorly monitored.
The species' presence in the specialist killifish hobby provides a degree of insurance: captive populations maintained by AKA members and their international counterparts exist at multiple collection strains, and the hobbyist literature documents breeding success across decades. Whether wild populations in the Inkisi system have been affected by any of these pressures since the 2009 assessment has not been formally re-evaluated.