Taxonomy & naming
Aphyosemion splendopleure was described by the German aquarist and amateur ichthyologist Carl Brüning in 1929, with the type locality recorded as Tiko in southwestern Cameroon — a coastal town near Mount Cameroon that sits at the edge of the Atlantic equatorial forest. Because Brüning's combination has since been moved from its original placement, his name appears in parentheses in the full authority as (Brüning, 1929). The valid combination is upheld in Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong), which remains the governing authority for nomenclature used on this site.
The species' placement within the large and taxonomically intricate genus Aphyosemion is contested at the subgeneric level. Several authors have treated it as a member of the subgenus Chromaphyosemion, a group of West and Central African killifishes characterised by vivid polychromatic male colouration, and the American Killifish Association database lists the subgeneric attribution accordingly. Other workers retain it within a broadly defined Aphyosemion sensu stricto pending a more comprehensive molecular revision. The distinction matters because Chromaphyosemion species tend to show strong population-level colour divergence, which is exactly what field collections of A. splendopleure reveal — the 'Tiko' colour form from the type locality differs from populations collected further south and east in Equatorial Guinea and Gabon.
Morphology
A small killifish, Aphyosemion splendopleure reaches a maximum of about 2 in total length (FishBase), with Seriously Fish giving 2–2.5 in standard length as the practical upper range — the difference reflecting the short tail extension that TL measurements include. In practice most aquarium specimens are sexually mature at 1.5–2 in. The body is slender and slightly compressed, the classic Aphyosemion build, with the upturned mouth positioned for surface and mid-water feeding.
Male colouration is the species' most compelling character. The flanks carry a base of iridescent apple-green to turquoise-green overlaid with red spotting and streaking, the pattern intensifying towards the rear of the body. The dorsal, caudal, and anal fins are edged with pigment that varies by population: in the Tiko form, green and red elements combine in an elaborate fin margin. Females are, as in most Aphyosemion, considerably plainer — a buff or olive body with faint spotting — but still attractively marked by the standards of many aquarium fish. Sexual dimorphism is immediately apparent: males are larger, more intensely pigmented, and carry more elaborately extended fin margins.
Habitat
The native range spans the coastal rainforest belt from southeastern Nigeria and the Cross River basin west through the southern Cameroon highlands and Littoral region, across Equatorial Guinea, and into northwestern Gabon. Altitude is generally low to moderate — the species is predominantly a lowland and submontane forest stream fish rather than a highland specialist. FishBase describes the habitat as quiet areas of small streams in coastal rainforest: clear to slightly tannin-stained water flowing over leaf litter and sandy or silty substrates, heavily shaded by closed forest canopy.
Water chemistry across this belt is characteristically soft and mildly acidic. Seriously Fish gives a temperature range of 72–79 °F with pH 6.0–7.2 and hardness of 54–268 ppm — a notably wider hardness span than the very soft blackwater some West African killies inhabit, suggesting the species tolerates somewhat mineralised water in the eastern and inland portions of its range. The key ecological requirement is intact, shaded forest cover: the small coastal streams in which A. splendopleure lives are temperature-buffered by canopy shade and fed by forest soils that maintain the low ionic concentration characteristic of rainforest hydrology.
Feeding
Like the great majority of small Aphyosemion species, A. splendopleure is a micropredator in the wild, feeding primarily on small invertebrates — aquatic insect larvae, microcrustaceans, worms, and surface-fallen terrestrial insects. The upturned mouth is well adapted for surface feeding, and in shaded forest streams the rain of invertebrates from the overhanging canopy forms a significant proportion of the diet alongside benthic prey items.
In captivity the species is straightforward to feed. Live or frozen daphnia, artemia (brine shrimp), bloodworm, and small tubifex are all accepted readily and provide the protein content needed to maintain colour and condition. Dry foods — micro-pellets and small quality flakes — are generally accepted once the fish are settled, though live and frozen foods remain important for conditioning breeding pairs and sustaining the full expression of male colouration.
Mating
Aphyosemion splendopleure is a non-annual killifish and a plant or substrate spawner — a distinction that separates it fundamentally from the annual species that bury desiccation-resistant eggs in dried substrate and are so often illustrated in popular killifish literature. In permanent rainforest streams there is no dry season that kills the adults and forces embryonic diapause; instead the fish live for two or more years and spawn continuously or in extended bursts throughout the year.
Male courtship involves persistent display and pursuit of females. Males are mildly territorial toward one another in confined spaces, and in aquaria a single male with two or three females is the recommended social unit to distribute male attention and minimise harassment. Spawning occurs when a male approaches a receptive female from the side, aligns his body alongside hers, and the pair press together briefly as eggs and sperm are released simultaneously. The eggs are adhesive and are deposited singly on fine-leaved plants, moss, substrate surfaces, or floating spawning mops — not buried in the substrate and not collected in a bubble nest.
Breeding
Egg deposition in A. splendopleure is a drawn-out process: the pair typically spawn a small number of eggs per session over days or weeks rather than releasing a single large clutch. Each egg is adhesive and spherical, deposited on vegetation, moss, or spawning mop fibres where it adheres and develops in place. Seriously Fish reports incubation of approximately 12 days when eggs are incubated submerged in water at typical temperatures; if eggs are removed to damp peat or moss (a common killifish husbandry technique that protects eggs from fungus and hungry adults), hatching takes around 18 days. There is no embryonic diapause — the eggs develop continuously and should not be dried.
Fry are small at hatching and require appropriately fine first foods: infusoria, commercial micro-fry food, or freshly hatched Artemia nauplii once the fry are large enough to handle them. Growth is steady at 72–75 °F. Separating eggs from adults by removing spawning mops every one to two weeks is the standard approach in hobbyist breeding, since adults will consume eggs if given the opportunity. Population-specific colour forms are maintained by isolating strains — mixing Tiko fish with fish from Equatorial Guinea populations, for example, is considered undesirable in killifish-keeping circles that prioritise wild-type locality authenticity.
In the aquarium
Aphyosemion splendopleure is well established in the killifish hobby and is regarded as a moderately easy species: hardier than some of the more demanding Aphyosemion but still requiring the soft, clean, well-oxygenated water that its rainforest-stream origin demands. The recommended aquarium is small — 10–15 US gal is ample for a breeding trio — well-planted with fine-leaved vegetation (java moss, hornwort, or synthetic spawning mops), dimly lit, and maintained at 72–75 °F. Temperatures above 79 °F cause stress and shorten lifespan; stability matters more than hitting a precise figure.
The species is shy and benefits from dense cover and dark substrate. Seriously Fish notes that males are mildly territorial with one another; a harem setup with one male and two or three females works well, or the species may be maintained in a species aquarium with several pairs if space permits. It is not an appropriate community fish with active or nippy tankmates, and any companion species must be small, peaceful, and compatible with the soft, acidic water parameters the killifish needs. The Tiko colour form is one of the more frequently encountered in the trade; other population-specific forms circulate among specialist killifish societies and through killifish association fish auctions.
Water changes of 20–30% weekly with aged, soft water are the backbone of husbandry. The species is sensitive to sudden chemistry changes and to accumulated nitrate; a sponge or small canister filter providing gentle flow without strong current suits its natural habitat.
Conservation
The IUCN Red List assessment of 2019, conducted by Olaosebikan and Moelants and published in 2020, assigns Aphyosemion splendopleure a status of Least Concern (LC). The assessors note that the species has a relatively broad range across the coastal forests of the Gulf of Guinea — southeastern Nigeria, Cameroon's Littoral and South regions, Equatorial Guinea, and northwestern Gabon — and that no evidence of a population decline sufficient to meet threat thresholds was available at the time of assessment. The full IUCN record is accessible at https://www.iucnredlist.org/species/182666/134752074.
The Least Concern designation should not be read as ecological complacency. The coastal rainforest belt in which A. splendopleure lives is among the most heavily pressured biomes in Africa: oil palm and rubber plantations continue to replace forest across the Cameroon Littoral and southern Equatorial Guinea, logging roads open previously inaccessible forest to hunting and agricultural encroachment, and sedimentation from cleared slopes degrades the clear, cool, shaded streams the species depends upon. The fish's reliance on intact, closed-canopy forest as a temperature buffer and water-chemistry regulator means that even partial forest clearance within a catchment can alter conditions beyond the species' tolerance. Monitoring of the small-stream communities of the Cross River basin and the Wouri and Mungo drainages in Cameroon — the core of the species' range — is limited, and the true trajectory of populations in disturbed landscapes is not well documented.