Taxonomy & naming
Sarotherodon lamprechti was described in 2011 by Dirk Neumann, Melanie L. J. Stiassny and Ulrich K. Schliewen in Zootaxa, in the same paper that erected its sympatric sibling Sarotherodon knauerae. The two are the only Sarotherodon endemic to Lake Ejagham, and the authors carved them out of the sprawling Sarotherodon galilaeus species complex after a morphometric study spanning 25 populations across northern and western Africa and the Levant. The holotype (ZSM 29929, in the Bavarian State Collection of Zoology, Munich) and an extensive paratype series come from the lake itself, in the Manyu Subdivision of Cameroon's South-West Province at roughly 5°45′N, 8°59′E. The genus Sarotherodon was raised by Rüppell in 1852 for African tilapias in which the male, or both parents, take the eggs into the mouth to brood — a reproductive mode that separates these fish from the substrate-spawning Tilapia (Coptodon) and from the maternal-mouthbrooding Oreochromis. Lake Ejagham is a textbook case in the sympatric-speciation literature: molecular work by Schliewen, Tautz and Pääbo (1994) and Schliewen et al. (2001) found the lake's cichlids to be monophyletic flocks descended from single riverine colonists, implying that Sarotherodon lamprechti and Sarotherodon knauerae split from one another inside the lake rather than arriving as already-distinct species. Molecular and pharyngeal-jaw evidence in the 2011 description corroborates that the two are each other's closest relatives.
Morphology
This is a small cichlid: the type series tops out at about 4 in standard length, making Sarotherodon lamprechti the larger member of the Ejagham Sarotherodon pair (its sibling Sarotherodon knauerae matures at barely 3 in). The body is short and deep, with a dorsal fin of 15–16 spines and 12–14 soft rays and an anal fin of 3 spines and 10–12 rays. The single most distinctive feature is the lower jaw, which is prognathous — it juts forward beyond the upper jaw — giving the fish an underbite found in none of its riverine relatives. The describers also point to a large, prominent upper lip (22.5–28.4% of head length), long pectoral fins that reach back to the last anal-fin spine, long pelvic fins, and an elongate ventral keel on the lower pharyngeal jaw. A reliable diagnostic at the bench is the pectoral-fin base, which is largely bare: scales there are restricted to at most the basal third, and their near-absence separates lamprechti from every congener. Gill rakers number 20–25, fewer than in Sarotherodon knauerae (24–30). In colour, males are normally golden, turning blackish below and blotchy dark brown above the lateral line when in breeding dress; females are a golden-grey with gold iridescence on the flanks and sometimes eight or nine faint lengthwise stripes. Juveniles wear nine or ten narrow vertical bars that fade with age.
Habitat
Sarotherodon lamprechti exists in exactly one place: Lake Ejagham, an oval lake roughly 1,050 by 700 metres across — about half a square kilometre — set at around 656 ft elevation in evergreen rainforest near the village of Eyumojok, in the Cross River basin of southwestern Cameroon. The lake is unusual for the region in that it is not a volcanic crater: it is most likely a solution basin formed by groundwater, and sediment cores date its origin to roughly 9,000 years ago, in the early Holocene, which sets a hard ceiling on the age of its endemic fishes. It is shallow by Cameroonian standards, with a maximum depth of about 56–59 ft, a low surrounding rim, and a single small outlet whose waterfall isolates the lake from the neighbouring Munaya River and keeps its fauna sealed in. The basin floor is a broad, flat blanket of fine organic mud offshore, fringed by a narrow belt of sandy shallows that dip steeply from the shoreline. Measured water chemistry is warm, soft-to-moderate and near-neutral: pH is circumneutral, conductivity ran 86–120 µS/cm in field measurements from 2008–2009, and monthly mean water temperatures sit around 77–82 °F in a climate where air temperatures swing from about 68–91 °F across a rainy season that runs April to October. Within the lake, Sarotherodon lamprechti is the open-water specialist of the pair, swarming through the pelagic zone and descending onto the deeper sandy bottom during the breeding season.
Feeding
Sarotherodon lamprechti is a pelagic phytoplanktivore — it feeds out in open water on suspended algae and plankton, with FishBase placing it at a low trophic level of about 2.4. This sets it apart ecologically from its sibling Sarotherodon knauerae, which is a bottom-oriented detritivore grazing soft and hard substrates near the shore, and the contrast in feeding niche is part of the evidence that the two species partitioned the lake's resources as they diverged. The fine, brush-like, flexible teeth that give the whole genus its name (Greek sarothron, a broom, plus odon, tooth) are exactly the dentition suited to combing fine food from the water and substrate. Across the genus Sarotherodon, such planktivorous and microphagous diets are typical, and in a small closed lake like Ejagham the open-water plankton crop is a resource the bottom-feeding tilapias largely leave untouched, giving lamprechti a lane of its own.
Mating
Breeding in this species is built around male-held courtship arenas on the lake bed. When the rains come, nuptial males in full golden-and-black colour excavate shallow pits — bowers — with narrow raised rims over sand. These bowers, 6.5–18.5 in across, double as territories and spawning sites. The larger ones tend to lie in the deeper sandy zones, 10–30 ft down, where bowers cluster close together so that neighbouring males are constantly within reach of one another; agonistic displays and skirmishes between bower-holders are a regular feature of these aggregations. Only occasionally, and only in shallow water less than 10 ft deep, do fully coloured males set up without a true bower, using instead a natural depression above a fallen tree or a flat stone. The clustering of bowers into a loose communal arena, with females moving through to choose among displaying males, is a lek-like system, and the agonistic jostling between adjacent males is the visible core of the species' pre-spawning behaviour.
Breeding
Sarotherodon lamprechti is a maternal mouthbrooder: after spawning over the male's bower, the female takes the fertilized eggs into her mouth and carries them there through incubation and the early free-swimming stage, while no nest or substrate brood is tended. This female-only care contrasts with several other Sarotherodon, in which the male or both parents brood, and it was one of the behavioural points the describers recorded for the lake's fish. Reproduction is seasonal, concentrated in the rainy months of August and September, when males establish their bowers in the deeper sandy areas and the fish gather to spawn. Direct counts of clutch size for Sarotherodon lamprechti have not been published; among Sarotherodon generally, mouthbrooded clutches are modest — on the order of tens to a few hundred comparatively large eggs, the trade-off for the protection oral incubation provides — and the limited carrying capacity of a brooding female's mouth caps fecundity well below that of open-water egg-scatterers. Both Ejagham Sarotherodon have been bred in captivity by hobbyists in Germany, but spawning and brood care have not been documented in detail in the wild.
In the aquarium
Sarotherodon lamprechti is essentially never seen in the general aquarium trade. It is a single-lake endemic listed as Critically Endangered, has no ornamental value beyond its scientific interest, and the only keeping on record is among a handful of specialist German aquarists who maintained stock following the species' description. Anyone who did keep it would be working from first principles rather than an established husbandry literature, so what follows is informed inference from the wild data rather than tested practice. This is a schooling, open-water mouthbrooder from a warm, soft, near-neutral lake, so it would want a long tank rather than a tall one — a footprint in the region of 59 in or more for a group, with a broad expanse of open swimming space and an area of fine sand for males to excavate bowers. Water should track the lake: about 77–82 °F, pH close to neutral (roughly 6.5–7.5), and low-to-moderate hardness, with conductivity in the lake's measured 86–120 µS/cm band rather than hard, mineral-rich water. As a planktivore it would take small suspended and flake foods readily, supplemented with finely divided live and frozen fare; vegetable-based and spirulina foods suit its microphagous, low-trophic-level diet. It is a group-spawning, lek-forming fish, so it should be kept in numbers, not pairs, and males will compete over bower sites — the usual tilapiine caution about intraspecific aggression among breeding males applies. Realistically, this is a conservation-and-research fish, not a community-tank candidate, and any captive population is best understood as an insurance colony for a species with a single, shrinking home.
Conservation
The IUCN Red List assesses Sarotherodon lamprechti as Critically Endangered under criteria B1ab(iii)+2ab(iii) — the assessment was carried out on 15 October 2014 and most recently published in 2023 (assessors Geelhand, Musschoot & Boden). Both the extent of occurrence and the area of occupancy are tiny — on the order of 2 mi², reflecting the species' confinement to a single half-square-kilometre lake and its surroundings — and it is known from this one location. The threats are concrete. Deforestation around the lake for oil-palm plantation and slash-and-burn agriculture is driving habitat decline, and the resulting erosion, compounded by unsustainable water extraction, degrades the lake itself. On top of that, a predatory catfish of the genus Parauchenoglanis was introduced from the neighbouring river system around 2001 and now competes with and preys upon the endemic cichlids — a serious pressure in a closed system whose fauna evolved in isolation behind an impassable waterfall. Because the entire global population of Sarotherodon lamprechti lives in one small, young, easily disturbed lake, it has no refuge: a single catchment-scale event could carry the species to extinction. Its conservation is inseparable from the integrity of Lake Ejagham as a whole — the same fragile basin that also holds its sibling Sarotherodon knauerae and an endemic flock of Coptodon tilapias found nowhere else.