Taxonomy & naming
The species was described by the Austrian ichthyologist Maximilian Holly in 1930 as Tilapia lohbergeri, in his "Synopsis der Süsswasserfische Kameruns," from a single specimen collected in Cameroon by Haberer. The holotype — a fish of roughly 3.5 in standard length plus a 1 in tail, registered NMW 13951 in the Naturhistorisches Museum Wien — remains the unique name-bearing type. Ethelwynn Trewavas redescribed and figured the fish in 1962, then placed it in its modern context in the landmark 1972 ecological monograph on the Barombi Mbo fishes (Trewavas, Green & Corbet). When Trewavas erected the genus Sarotherodon in 1973 to hold the African paternal and biparental mouthbrooders — separating them from the maternal mouthbrooders left in Oreochromis and the substrate-spawners in Tilapia — lohbergeri moved with them; the combination Sarotherodon lohbergeri (Holly, 1930) was formalised by Trewavas & Teugels (1991) and is the name accepted today by the Catalog of Fishes and FishBase. The species sits inside the Barombi Mbo flock, a clade of eleven endemic cichlids (the genera Sarotherodon, Konia, Myaka, Pungu and Stomatepia) that molecular work by Schliewen and colleagues has shown to be monophyletic — all descended from a single colonisation of the crater by a Sarotherodon galilaeus-like riverine founder. Trewavas read lohbergeri as a specialised offshoot of that ancestral stock, allying it loosely with the Sarotherodon linnellii–caroli group and noting a resemblance in colour pattern to Konia eisentrauti. The epithet honours Karl Lohberger, an obscure contemporary of Holly's at the Vienna museum.
Morphology
Sarotherodon lohbergeri is a modest, short-and-deep-bodied cichlid reaching about 6.5 in standard length (the largest recorded specimen), with most fish considerably smaller; the holotype was around 3.5 in. The ground colour is a plain silver-grey, crossed by a mid-lateral black band that is interrupted anteriorly over the caudal peduncle, with the dark blotches often loosely arranged into a mid-lateral and an upper longitudinal row — a pattern Trewavas likened to that of Konia eisentrauti. Tellingly for a Sarotherodon, the species lacks the so-called tilapia-mark (the dark ocellus on the soft dorsal fin seen in many substrate-spawning tilapias). Fin counts run to 15–17 dorsal spines and 10–12 soft rays, 3 anal spines and 8–10 soft rays, with 29 vertebrae and 30–31 lateral-line scales; the lower limb of the first gill arch bears 14–18 rakers. The head is moderate (33–38% of standard length). The defining feature is the dentition of a scraper: the jaw teeth have slender shafts and broad, flattened crowns, set in several rows, with fine, close-set unicuspid teeth on broad pharyngeal plates — the toolkit of a fish built to rasp a film of algae off hard surfaces. Sexual dimorphism is slight and there is no marked breeding dichromatism; mature fish of both sexes develop variable black areas on the lower jaw and underside of the head, an effect Trewavas found to track gonad condition rather than sex.
Habitat
The entire world range of this fish is Lake Barombi Mbo, a crater lake about 2 mi across (roughly 3 mi² of open water within a ~4 mi² catchment) lying near the town of Kumba in southwest Cameroon, part of the Cameroon Volcanic Line. The lake is genuinely isolated: cataracts on its single short outflow seal it off from neighbouring river systems, which is exactly why its fish fauna could radiate in place. A handful of records also come from the lake's inflowing Kake stream and from the Kumba stream on the outlet, but for practical purposes lohbergeri is a Barombi Mbo endemic, placed by FEOW in the Southern Gulf of Guinea Drainages ecoregion. The lake is deep — over 328 ft at the centre — and strongly stratified: a warm, oxygenated surface layer overlies cold, permanently anoxic deep water, so all the fish life is confined to the upper few tens of metres. Surface temperatures run warm and stable, around 77–84 °F through the year (FishBase cites a 77–81 °F band), and surface pH sits near neutral (about 7.0–7.5), grading to mildly acidic with depth. The water is soft, stained with tannins and organic debris, and the margins are floored with sand, pebbles, leaf litter, submerged wood and rock with patches of freshwater sponge. Within this setting lohbergeri keeps to the shallows, favouring zones with submerged wooden or stony structure, and was historically the most abundant fish in shallow water.
Feeding
Sarotherodon lohbergeri is the flock's dedicated aufwuchs grazer — the specialist that feeds on the epilithic and epiphytic film of filamentous algae and the diatoms, rhizopods (Arcella, Euglypha, Difflugia), bdelloid rotifers and organic debris caught within it. Trewavas and colleagues watched adults feed by opening the mouth very wide and clamping it flat against the surface of a rock, as if sucking the material in, then drawing the broad-crowned teeth across the substrate; the same fish grazed epibionts from the leaves and stems of the waterweed Najas, and large shoals worked submerged logs and sponge-crusted stones. Stomach analyses confirmed organic debris as the bulk of the diet, with the algae, protozoans and rotifers of the biofilm alongside it. Its low trophic level (about 2.2) reflects this near-herbivorous, surface-rasping niche. In the broader story of the flock, Trewavas interpreted lohbergeri as the lineage that, faced with competition for limited aufwuchs, became the specialised rock-and-leaf scraper — diverging from a more generalist ancestor while siblings turned instead to sand-sifting, bottom invertebrates, phytoplankton or night feeding.
Mating
Like its congeners, Sarotherodon lohbergeri is a mouthbrooder rather than a substrate spawner, and its social biology reflects that. The species lacks the bright breeding colours and strong sexual dichromatism that, in many cichlids, signal a male defending a display arena to attract females — an absence Trewavas and later FishBase read as the hallmark of a biparental, non-territorial mouthbrooding system rather than the harem polygamy of the maternal-only tilapias. Reports indicate the fish forms temporary pair bonds that last through incubation and brood care, with both partners potentially serving as incubators. Detailed in-situ courtship has not been documented for this species in the way it has for some Rift Lake cichlids; what is on record is a fish that lives much of its life in loose shallow-water shoals grazing rock and weed, pairing off transiently when conditions are right rather than holding long-term territories. The black chin and throat that mature fish of both sexes develop appear tied to reproductive condition and may play a role in spawning signalling, but the system is best summarised honestly as a temporarily paired mouthbrooder whose fine courtship details remain poorly described.
Breeding
Breeding in Sarotherodon lohbergeri follows the genus pattern: the parents produce a small number of large, yolk-rich eggs and brood the developing young inside the mouth, so no nest or guarded substrate clutch is involved. Trewavas measured ripe ovarian eggs at roughly 0.5 in long diameter — large, as expected for a mouthbrooder investing heavily in each offspring — and the corresponding clutches are small: one examined female carried 13 eggs in one ovary and 27 in the other, on the order of forty eggs, consistent with the low fecundity seen across the Barombi Mbo Sarotherodon. The absence of sexual dichromatism points to a biparental mouthbrooding function, with FishBase noting that both sexes are possible incubators and that the pair bond persists for the duration of incubation and brood care; after the eggs are taken up they are carried, oxygenated in the buccal cavity and the fry sheltered there until they can fend for themselves, after which released young likely shoal in the shallows where the adults graze. Specific figures for incubation time, fry size at release and spawning triggers have not been published for this species, and are given here as genus-typical rather than measured.
In the aquarium
Sarotherodon lohbergeri is not an aquarium-trade fish in any ordinary sense. It is a Critically Endangered single-lake endemic, essentially never offered commercially, and the few specimens that have reached aquaria have done so through specialist and conservation-minded channels rather than the hobby pipeline — a male photographed in Anton Lamboj's tank in Austria is among the rare documented captive examples. The wider Barombi Mbo flock has a reputation among the handful of aquarists who have worked with it (for instance the New England Cichlid Association's species-tank programme) as difficult to sustain, with the main bottleneck being getting offspring reliably grown on. Anyone in a legitimate position to keep it should treat it as a conservation responsibility rather than an ornamental, and recreate the lake as closely as possible: a long tank with open shallow-water swimming room for a shoal, plenty of smooth rock and submerged wood to host the algal film the fish is built to graze, a sand and leaf-litter floor, and warm, soft, near-neutral water (around 77–82 °F, pH ~6.5–7.5) kept very clean and well oxygenated, since these fish come from a lake whose deep water is lethally anoxic and whose surface layer is correspondingly oxygen-dependent. Diet should lean herbivorous — quality spirulina and algae-based foods plus whatever natural aufwuchs the tank can grow — rather than the meaty, protein-heavy fare some tilapias are pushed on. As a mouthbrooder with a small clutch it breeds slowly even when it does breed, so it is a fish for the patient, not the casual keeper. For almost everyone, the realistic relationship with this species is to support the protection of Barombi Mbo itself, not to keep it in glass.
Conservation
The IUCN Red List assesses Sarotherodon lohbergeri as Critically Endangered (criteria B1ab(iii)+2ab(iii)), assessed on 16 February 2009 by T. Moelants and published in 2010. The reasoning is geographic: the fish exists only in Lake Barombi Mbo, a basin of about 4 mi², so any deterioration of that one lake threatens the entire species at once. The assessment flags a convergent set of pressures on the crater — sedimentation and nutrient pollution from oil-palm plantations and slash-and-burn agriculture on the surrounding slopes, growing water abstraction for the nearby town of Kumba, proposed tourism development, and deforestation that, by altering local winds, could disturb the lake's delicate stratification and trigger oxygen depletion. Layered over these is a rarer hazard shared by Cameroon's volcanic lakes: the risk of a limnic eruption, the catastrophic "burping" of dissolved CO2 from deep water that devastated nearby Lakes Nyos and Monoun, which for a fauna confined to a thin oxygenated surface layer would be ruinous. Because the whole eleven-species flock is squeezed into this single small lake, lohbergeri's survival is bound up with the conservation of Barombi Mbo as a whole — one of the most scientifically important and most fragile cichlid waters in Africa. It carries no CITES listing.