Taxonomy & naming
Aphyosemion campomaanense was described by Austrian killifish specialist Arthur Radda in 1975. The original description placed it in Aphyosemion, the broad aggregate genus that historically absorbed most West and Central African non-annual killies. Subsequent molecular and morphological work led to the elevation of the subgenus Chromaphyosemion to full generic rank, and Eschmeyer's Catalog of Fishes now records the valid combination as Aphyosemion campomaanense (Radda, 1975), with the parenthetical authority indicating the original generic assignment has changed.
The genus Chromaphyosemion — 'coloured Aphyosemion' — is concentrated in the Gulf of Guinea lowland rainforest zone from southeastern Nigeria through Cameroon and into Gabon. The group's members were informally grouped under the 'bivittatum complex' in older killifish literature, referencing a common pattern of double lateral stripe elements, though not all members express this pattern equally clearly. Aphyosemion campomaanense belongs to this western Cameroonian radiation. The specific epithet campomaanense refers to the Campo-Ma'an region of southwestern Cameroon, which encompasses both the Campo River catchment and the Ma'an district, now largely coincident with Campo-Ma'an National Park.
This fish was long listed as Chromaphyosemion campomaanense; Eschmeyer's Catalog of Fishes places the species in Aphyosemion, and the current combination Aphyosemion campomaanense is followed here.
Morphology
Aphyosemion campomaanense is a small and slender-bodied killifish. FishBase records a maximum standard length of 2.2 in for females and 1.6 in for males — an unusual reversal of the typical killifish pattern in which males are the larger sex, though the difference here is modest and likely reflects the typically stockier build of ripe females.
Males display the vivid colouration characteristic of the genus: a ground colour of reddish-brown to olive-green on the flanks, overlaid with rows of red or orange-red spots and dashes, and often a bluish-green iridescent sheen to the lower flanks. The unpaired fins are typically elaborately patterned with red spotting and a blue or yellow marginal band, patterns that vary enough between collection localities to make population identification possible by experienced keepers. Females are, as in nearly all Chromaphyosemion, considerably plainer — brownish overall with little or no fin colour — a camouflage strategy consistent with the female's role as the sex responsible for egg guarding and substrate selection during spawning.
Habitat
The type locality is recorded as the Campo-Ma'an National Park, southwestern Cameroon. Field-collected water parameters from Cameroonian Aphyosemion/Chromaphyosemion habitats in comparable rainforest streams show temperatures in the range of 75–81 °F, with pH running slightly acidic — Scheel's field records from similar habitats give pH around 6.5, and the AKA species profile records pH 7.0 and hardness of 10 dH for captive reference conditions. The habitat is characterised by FishBase as small streams and shallow pools within rainforest, with the fish concentrated close to the banks where overhanging vegetation, root systems, and leaf litter provide cover.
These are slow-moving to nearly stagnant waterbodies shaded by closed-canopy forest, with soft substrates and often a light accumulation of leaf litter. The soft, moderately acidic water chemistry is consistent with Central African lowland rainforest streams generally. Nkoelon, one of the documented collection points coded ABC 05/55, falls within the same southwestern Cameroonian rainforest belt.
Feeding
In the wild, Aphyosemion campomaanense is an insectivore and invertivore, as is typical for the genus. It forages at or near the water surface and in mid-water among vegetation and roots, taking small insects — both fallen surface prey and emergent aquatic larvae — along with micro-crustaceans, small worms, and zooplankton.
In the aquarium it accepts live and frozen foods readily: daphnia, artemia nauplii and adults, chironomid larvae (bloodworm), and small tubifex are all suitable. Dry foods in the form of high-quality small granules or flake are usually accepted after acclimatisation, though a diet based substantially on live or frozen invertebrate prey supports the best colouration and conditioning. Feeding in small amounts twice daily, with occasional fasting days, suits the species.
Mating
Aphyosemion campomaanense is a non-annual, plant-spawning killifish — a distinction that separates it fundamentally from the annual, soil-burying species that dominate killifish popular culture. Rather than producing diapausing eggs buried in substrate to wait out a dry season, this species lives in permanent or near-permanent rainforest waterbodies and spawns by depositing small numbers of adhesive eggs on fine-leaved aquatic plants, submerged roots, or floating spawning mops over an extended period.
Males display actively to females using spread fins and lateral body posturing, showing off the species' colouration at close range. Pairing is temporary rather than long-term; successful courtship ends in a brief side-by-side spawning position in which one or two eggs are fertilised and placed adhesively on vegetation. The pair then separate, and spawning bouts are repeated over days and weeks. This protracted, low-output spawning mode is typical of the bivittatum-group Chromaphyosemion.
Breeding
Eggs are deposited individually or in very small numbers on plants or mop fibres and left entirely without parental care. FishBase records an incubation period of 2–3 weeks at typical aquarium temperatures (approximately 75 °F), consistent with the Tropical Fish Hobbyist Magazine characterisation of Chromaphyosemion subgenus eggs as hatching in 2–3 weeks with no diapause. The eggs are small and delicate; they can be left on the spawning mop and moved to a separate hatching container, or the entire mop can be transferred and checked regularly for fry.
Fry are tiny at hatching and require appropriately sized first foods — infusoria, freshly hatched artemia nauplii, or commercial micro-fry foods. They are free-swimming almost immediately and grow steadily under good husbandry. Because the species breeds continuously at low volume rather than in seasonal mass-spawning events, a small colony in a well-planted tank will produce a trickle of fry throughout the year if a mop or fine-leaved plant is provided and inspected regularly. Sexual maturity is reached at a few months of age. Hobbyist breeding records are documented in the British Killifish Association archives, where Colin McCourt's observations on A. campomaanense (under the former Aphyosemion combination) confirm its tractability in captivity.
In the aquarium
Aphyosemion campomaanense is well regarded in specialist killifish circles as one of the more accessible Chromaphyosemion species. A small aquarium of 8–16 US gal, densely planted or fitted with floating spawning mops, suits a pair or small group. Water should be soft (targeting the reference 10 dH or lower), near-neutral to slightly acidic (pH 6.5–7.0), and maintained at 72–79 °F. The AKA profile gives 75 °F as a suitable temperature. Tannin-stained water produced by peat filtration or Indian almond leaves is appreciated and reflects the leaf-litter streams of the type locality.
The species is not aggressive but males will spar with each other, so a single-male setup or a well-structured tank with sight barriers is advisable. It can be kept in a community of similarly sized, non-competitive fish (small rasboras, nano tetras, or other small African fish), but its preference for cooler, very soft water means tankmates must be chosen with matching chemistry requirements. The main challenge for hobbyists is locating stock with reliable population provenance — the killifish community maintains coded collection lines, and specimens labelled with a recognised locality code (such as the Nkoelon ABC 05/55 collection) carry known genetic identity, which matters both for appreciation of the fish's natural variation and for any future conservation-relevant captive breeding.
Conservation
Aphyosemion campomaanense has not been formally assessed by the IUCN Red List and carries a Not Evaluated (NE) status. Its entire known range lies within or immediately adjacent to Campo-Ma'an National Park, which affords a degree of legal protection to the forest streams it inhabits. This restricted range makes it inherently vulnerable: a species confined to a single protected-area catchment has limited capacity to recolonise if local extirpation occurs.
The primary threats facing rainforest killifish in southwestern Cameroon are deforestation at park margins, small-scale agriculture encroaching on stream-bank vegetation, and any hydrological disruption that reduces the permanence of shallow forest pools. The introduction of non-native species — particularly mosquitofish (Gambusia spp.) — into West and Central African stream systems has been implicated in killifish declines elsewhere in the region, though its status in the Campo-Ma'an catchment specifically is not documented in the available literature. The killifish hobby contributes meaningfully to the informal conservation of narrow-range species like this one: population-coded captive lines maintained by specialist societies represent an ex-situ reservoir in the event of range contraction in the wild.