Taxonomy & naming
Hemichromis camerounensis was described in 2021 by Arnold Roger Bitja-Nyom, Jean-François Agnèse, Antoine Pariselle, Charles Félix Bilong-Bilong, André Gilles and Jos Snoeks, in a systematic revision of the large "five-spotted" Hemichromis complex of West Africa and Lower Guinea published in the journal Hydrobiologia (volume 848, pages 3779–3803). The work combined morphometrics — measurements, meristics and colour pattern — with mitochondrial (cytochrome b) sequence data across roughly 100 populations, and resolved three principal lineages. West African material, including the Lake Bosumtwi endemic long called Hemichromis frempongi, clustered with Hemichromis fasciatus; southern Lower Guinea material, including the type population of Hemichromis elongatus from Gabon, formed a weakly resolved second cluster; and the populations of northern Lower Guinea (the Atlantic coastal basins of Cameroon) together with the upper Chad basin formed a strongly supported third clade, which the authors named Hemichromis camerounensis. The holotype (MRAC 2015.019.P.0001) is held at the Royal Museum for Central Africa in Tervuren, Belgium, with paratypes in the same collection. The type locality is the Avoo River in the Sanaga basin, between the villages of Batchenga and Ndji in Cameroon (about 04°19′36″N, 11°40′22″E). The genus Hemichromis was erected by Wilhelm Peters in 1858; this species sits in the subfamily Pseudocrenilabrinae of the family Cichlidae. Because the fish was previously identified as Hemichromis fasciatus or as an "elongatus-like" form, older literature and museum lots from coastal Cameroon and the Chad basin that predate 2021 may refer to this species under those earlier names.
Morphology
This is one of the larger members of the genus. FishBase lists a maximum of 5.5 in standard length from the original description, and wild lake fish measured by Bitja-Nyom and colleagues reached about 7 in total length and nearly 90 g. The body is moderately elongate and deep-bodied for a Hemichromis, with 14–15 dorsal spines, 10–12 soft dorsal rays and 8–11 soft anal rays. Colour in life ranges over the belly and head from dark to whitish, sometimes reddish, and the flanks carry the dark vertical bars and the row of dark blotches characteristic of the "five-spotted" Hemichromis lineage. The single most useful field character is the gill cover: live or freshly caught Hemichromis camerounensis show two distinct red spots, one on either side of the large black opercular blotch, whereas Hemichromis fasciatus shows no or just one red spot and Hemichromis elongatus shows a single red spot or a reddish-yellowish mixture above the black blotch. Beyond colour, the species is separated from its congeners by a suite of overlapping morphometric and meristic differences — generally a lower count of soft dorsal rays, fewer cheek scales, large eyes, a broad interorbital region and a broad head — and by the shape of the lower pharyngeal jaw, which is more V-shaped with a longer tooth-bearing area than the more Y-shaped jaw of Hemichromis fasciatus. Sexual dimorphism in this genus is subtle: the sexes are similar in pattern, mature males tend to grow slightly larger and females become noticeably deeper-bodied and more intensely coloured when ready to spawn, the same breeding-dress logic seen across Hemichromis.
Habitat
Hemichromis camerounensis is a fish of the Atlantic-draining coastal basins of Cameroon and south-eastern Nigeria, recorded from the Cross River in the north-west down to the Lobé River, and it also occupies the upper Chad (Logone) basin in northern Cameroon — an interior population whose presence helped define the new species. Within this range it tolerates a strikingly wide environmental envelope, from warm lowland coastal rivers and lagoons to highland crater lakes on the Adamawa Plateau. Detailed in-situ chemistry comes from three Adamawa lakes near Ngaoundéré studied by Bitja-Nyom and colleagues: in Lakes Bini and Dang, both connected to the Chad-basin Bini River by outlets, the surface water was very soft and markedly acidic (pH about 5.1–5.2, conductivity roughly 17–27 µS/cm, total dissolved solids around 10–17 ppm) at temperatures near 72–73 °F, while the isolated, outlet-less crater Lake Tizong was far more mineralised (pH about 7.5, conductivity around 260 µS/cm) and held a stunted, dwarfed population. Tizong is a deep volcanic crater (maximum depth about 157 ft, mean 85 ft), but these cichlids are fish of the productive littoral and surface waters rather than the depths; the highland lakes sit at around 1,065–1,249 ft elevation. Lowland coastal populations live in warmer water than the cool plateau lakes. Across its range the species shows clear morphological plasticity, with the insular Tizong population diverging toward smaller size, a narrower head and fewer gill rakers — a textbook example of rapid in-lake evolution in the crater lakes of the Cameroon Volcanic Line.
Feeding
Like the other large, banded Hemichromis, Hemichromis camerounensis is a predator rather than a peaceful micro-grazer. FishBase places it at a trophic level near 3.4, consistent with a carnivore that takes small fishes, aquatic insects, crustaceans and other invertebrates. The deep, V-shaped lower pharyngeal jaw with its long tooth patch is the crushing apparatus of a generalist carnivore able to process hard-bodied prey. The "five-spotted" members of the genus, including Hemichromis fasciatus to which this species was long assigned, are well known as ambush and pursuit predators on smaller fish — to the point that they are regarded as serious piscivores in West African fisheries and ponds — and the same predatory habit applies here. In the crater and floodplain habitats it occupies, Hemichromis camerounensis functions as a mid-level predator of the littoral community, hunting among marginal vegetation and over the bottom; the higher condition factors recorded in the food-rich, well-oxygenated outlet lakes Bini and Dang, versus the impoverished closed lake Tizong, underline how directly its growth tracks prey availability.
Mating
No dedicated behavioural study of pairing in Hemichromis camerounensis has yet been published, so its mating biology is read from the well-documented behaviour of the genus. Hemichromis are monogamous, biparental cichlids that form a bonded pair and together hold and defend a territory through the breeding cycle. Pair formation is preceded by mutual display, lateral spreading of the fins, jaw-locking trials of strength and an intensification of colour, the females in particular flushing dark and reddish as they ripen. Once a pair forms, both fish become strongly territorial and will drive other fish — including conspecifics — out of the chosen spawning area. In the large predatory species this aggression is pronounced, and an unpaired or mismatched fish placed with a determined individual is at real risk; courtship in this group is as much a test of compatibility as of readiness, and a settled, evenly matched pair is the foundation of a successful spawn.
Breeding
Reproduction in Hemichromis camerounensis has not been described in detail, but every member of the genus is a biparental open substrate (nest) spawner, and there is no reason to expect this species to differ. In Hemichromis the pair cleans a flat, firm surface — a rock, a root, a leaf or a pit excavated in the substrate — and the female deposits adhesive eggs in neat rows that the male fertilises as he passes. Both parents then tend the clutch, fanning it with their pectoral fins to keep it oxygenated and removing dead or fungused eggs, while jointly repelling intruders. After the eggs hatch the wrigglers are commonly moved to one or more pre-dug pits, and once the fry become free-swimming the parents lead and guard the school, often herding it back to cover at any threat. Fecundity figures specific to this species are not on record; congeners in the large five-spotted group are highly productive, the closely related Hemichromis fasciatus laying clutches that range from roughly a hundred to well over a thousand eggs (means near 850, with up to ~2,500 reported), so a similar order of magnitude is plausible here. Warmth, soft water and abundant live food bring the fish into condition; spawning in the genus is typically triggered by the cleaning and defence of a suitable surface within an established territory.
In the aquarium
Hemichromis camerounensis is a newly described, scientifically known fish that is essentially absent from the ornamental trade, so there is no established body of hobby experience specific to it; what follows is reasoned from its biology and from the keeping of its close relatives. This is not a small red jewel cichlid — it is a robust predator that approaches 6 in or more, and it should be housed and stocked accordingly. A single pair needs a large tank: a footprint on the order of 47 in (about 120 US gal) is a sensible minimum, more if other fish are present, because territorial and predatory aggression are the defining husbandry challenges of the big banded Hemichromis. Tankmates must be too large to be eaten and robust enough to weather a breeding pair's defence; small fish will be hunted, and conspecifics or other cichlids may be attacked outright, especially once a pair forms. The field data suggest considerable flexibility on water chemistry — wild populations thrive both in very soft, acidic water (pH around 5, very low conductivity) in the Adamawa outlet lakes and in distinctly harder, near-neutral to slightly alkaline water (pH ~7.5) in Lake Tizong — so a well-kept aquarium anywhere in the range of pH ~6.0–7.5 and soft-to-moderate hardness should suit it, provided the water is clean and well filtered. Temperature is worth thinking about: the highland lake populations live around a cool 72–73 °F, while lowland coastal fish experience warmer water, so a moderate tropical range of roughly 73–81 °F is reasonable, avoiding the high-20s-and-above that some keepers default to. Provide firm flat rocks, wood and a few caves to serve as spawning sites and to break the line of sight and diffuse aggression, with a sand or fine-gravel bottom. Diet is straightforward for a carnivore: a varied menu of meaty frozen and live foods — earthworms, prawn, mysis, chironomid larvae — alongside good-quality sinking carnivore pellets. The honest summary is that this is a fish for the specialist or public-aquarium keeper who can source it legitimately and give a predatory West African cichlid the space and tankmate planning it demands.
Conservation
Hemichromis camerounensis has not yet been assessed by the IUCN Red List — its status is Not Evaluated, unsurprising for a species described only in 2021. No data on population trend or total range area have been formally compiled. Several general considerations frame its outlook. On the one hand, the species is reasonably widespread across the Atlantic coastal basins of Cameroon and south-eastern Nigeria and into the upper Chad basin, occupies a broad spectrum of habitats from lowland rivers to highland crater lakes, and is ecologically flexible — all traits that buffer extinction risk. On the other, some of its populations are restricted and locally pressured: the Adamawa crater lakes that hold it, such as Bini, Dang and Tizong, are small, are subject to uncontrolled fishing, agriculture, livestock and shoreline disturbance, and in the case of Tizong support a genetically and morphologically distinctive, isolated population whose origin and future are of particular interest. As an edible fish caught in gillnet fisheries on those lakes, it is harvested locally. The wider Lower Guinea and Cameroon Volcanic Line freshwaters are recognised as a biodiversity hotspot under pressure from deforestation, pollution and habitat alteration; a formal Red List assessment, together with basic data on its abundance and reproduction, would be the logical next step now that the species is recognised.