Taxonomy & naming
The hump-back bream was described by the British ichthyologist Charles Tate Regan in 1920, in his paper 'A revision of the African cichlid fishes of the genus Tylochromis' (Annals and Magazine of Natural History, ser. 9, vol. 5), the same work in which he erected the genus itself. The type series was collected at Lake Bangweulu (then spelled 'Bangwelu'), Zambia, and is held in the Natural History Museum, London; Melanie Stiassny designated the lectotype (BMNH 1905.11.20.25) in her 1989 monograph, with four paralectotypes from the same registration lots. Eschmeyer's Catalog of Fishes lists the name as valid as originally combined, Tylochromis bangwelensis Regan 1920, with no junior synonyms. The species sits within the small tribe Tylochromini, of which Tylochromis is the only genus — a basal African cichlid lineage that Stiassny (1989, 1990) placed near the root of the African radiation, well outside the haplochromine and lamprologine assemblages of the Great Lakes. Her revision tidied the species Regan had named, and bangwelensis came through it intact. Older literature reporting the fish from the Luvua, upper Lualaba, and lakes Mweru and Upemba is now treated as misidentification (those Mweru–Luapula populations belong to the related Tylochromis mylodon); the genuine range of Tylochromis bangwelensis is anchored on the Bangweulu–Chambeshi side of the watershed.
Morphology
Tylochromis bangwelensis is a heavy, laterally compressed, large-scaled cichlid with the steep forehead and small, low-set mouth typical of the genus — a build that reads instantly as a bottom feeder rather than a midwater hunter, and the source of the English name 'hump-back bream.' FishBase gives a maximum total length of about 11 in, while a Ford–Walford growth analysis of more than 1,800 Bangweulu fish estimated an asymptotic length (L∞) near 13.5 in, so large individuals in the fishery run somewhat beyond the commonly cited maximum. The fin formula is 13–15 dorsal spines and 14–16 soft rays, three anal spines and 7–8 anal soft rays, with 28 vertebrae. The diagnostic feature Stiassny keyed on is the lower lateral line, which extends unusually far forward; like all Tylochromis the species also carries a robust lower pharyngeal jaw bearing enlarged, mill-like (molariform) teeth for crushing hard prey, two lateral lines, and a distinctive pattern of head laterosensory pores. Sexual dimorphism is weak in external form — the sexes are most reliably told apart by the gonads or by a brooding female's distended throat — which is consistent with the genus's role-divided, non-pair-bonding biology rather than the bright dichromatism of many haplochromines.
Habitat
The hump-back bream is restricted to the Bangweulu–Chambeshi side of the upper Congo (Luapula) drainage: Lake Bangweulu and its surrounding swamps, the adjoining Luapula, and the Chambeshi River, spanning the Democratic Republic of the Congo and northern Zambia. The Bangweulu lakes-and-swamps complex is a vast, shallow floodplain wetland — roughly 10°15′–12°30′ S and 29°30′–30°30′ E — set in a hollow on an ancient cratonic platform, with marked seasonal water-level swings driven by the rains. It is a warm, soft, often turbid blackwater-to-clearwater system rather than the hard, alkaline rift water of Tanganyika; FishBase classes the fish as freshwater and benthopelagic in the tropical zone. Tylochromis bangwelensis is an open-water and inshore animal of the lake proper and its swamp margins, working soft sand-and-mud bottoms; brooding females and young keep close inshore among Eleocharis reed and other emergent vegetation. No detailed in-situ chemistry has been published for this species specifically, but the wider Bangweulu wetland is characteristically warm (water temperatures broadly in the low-to-high 20s °C) and weakly mineralized with near-neutral, seasonally variable pH — the soft-water, floodplain end of the cichlid spectrum. Depth is shallow throughout: the complex is a few metres deep at most over much of its area, and the fish is a creature of those shallow inshore and swamp-edge waters.
Feeding
Tylochromis bangwelensis is a benthic, invertebrate-leaning feeder, and in Lake Bangweulu its predominant food is the lake-fly (a chaoborid/chironomid midge) in its aquatic larval stages — the same dense seasonal swarms of soft-bodied larvae that fuel much of the lake's fish production. It also takes plant material, and FishBase places it at a trophic level of about 3.2, squarely that of an invertebrate-feeder rather than a piscivore. Local fishery work describes it variously as a zooplankton and lake-fly feeder; functionally it is a generalist bottom forager that sifts soft sediment and grubs the substrate for small prey. The genus-defining adaptation behind this — the robust lower pharyngeal jaw with molariform teeth — equips Tylochromis to crush hard-shelled prey such as snails (durophagy), and while Tylochromis bangwelensis leans more on soft midge larvae than do the most extreme snail-crushers of the genus (like the Mweru Tylochromis mylodon), it carries the same crushing apparatus. The wet-season flood pulse drives its feeding calendar: flooding stimulates a surge of algae, phytoplankton, zooplankton and insect production in the swamps, and the fast growth coefficient measured for the species (k ≈ 0.84) reflects how richly it cashes in on that seasonal abundance.
Mating
Like all Tylochromis, the hump-back bream is a maternal mouthbrooder that does not form lasting pair bonds — the African mouthbrooding template of the haplochromines and tilapiines rather than the biparental cave-spawning of the Tanganyikan lamprologines. The consequence for social structure is that the male's investment ends essentially at fertilization, and the female alone carries and defends the brood. The fish is not a rock-bound territorial specialist holding a permanent site; it is a roving benthic forager of open sand and swamp margins, and reproduction is tied to the seasonal hydrology of the wetland rather than to a defended reef. At high water the adults move out of the open lake into the adjacent flooded swamps — their breeding grounds — to spawn, a migration that places the vulnerable early stages in the sheltered, food-rich, reed-screened shallows. Detailed in-situ courtship of this species has not been documented, and that gap is worth stating plainly rather than papering over; what is established is the timing (a single breeding push at the close of the rains) and the mode (female-only buccal incubation).
Breeding
Breeding in Tylochromis bangwelensis is concentrated into a single annual spawning period toward the end of the rainy season, timed to the flood that opens the swamp nurseries. The female is a buccal (mouth) brooder: she incubates the eggs and then the larvae in her mouth, and observers have found young still attached to the yolk sac in the mouth of a parent that is already on the verge of spawning again — evidence of how tightly the cycle is packed into the high-water window. After release the fry keep closer inshore among Eleocharis reed and other vegetation, where they are a favoured prey of the tiger-fish (Hydrocynus) that hunt the same waters. As with the rest of the genus, this is a low-fecundity, large-egg strategy — congeners such as the Tanganyikan Tylochromis polylepis have been recorded carrying on the order of 100 large (~0.5 in) eggs — trading egg numbers for well-developed, mouth-protected young; a precise clutch count for Tylochromis bangwelensis itself has not been published, so that figure is best read as genus-typical rather than measured. Length at first maturity is about 4.5 in (range roughly 4.5 in), so the fish breeds while still well short of its maximum size. The species has never been bred in captivity in any documented way; everything known about its reproduction comes from the wild Bangweulu fishery.
In the aquarium
Tylochromis bangwelensis is, for practical purposes, not an aquarium fish. It is a commercial food fish of the Bangweulu lakes-and-swamps fishery — locally called nsangula — and is essentially never offered in the ornamental trade; there is no body of hobbyist keeping or breeding experience for this species to draw on. Anyone wanting to keep a Tylochromis at all is far more likely to encounter the occasionally-traded Tanganyikan Tylochromis polylepis, and the husbandry lessons transfer: these are large (here approaching 12 in), deep-bodied, sediment-dependent sand-sifters that need a long tank with a generous open sand bed, not a rockwork-stuffed setup, and that ask for far more space than their behaviour suggests at first. The genuine hard requirements that would apply to Tylochromis bangwelensis are an open soft substrate it can work constantly, strong filtration to cope with the detritus a sifter kicks up, and — importantly for this genus — excellent oxygenation, since Tylochromis are noted for marked intolerance of low oxygen. Unlike its hard-water rift relatives, this is a soft, warm, near-neutral floodplain fish, so it would want warm water in the mid-to-high 20s °C and soft, modestly mineralized conditions rather than buffered rift chemistry. The honest verdict is that this is a wild-harvested African food fish documented from fisheries science, not from aquaria; treat any husbandry note here as extrapolation from the genus, and recognise that the species itself has no real track record in captivity.
Conservation
The IUCN Red List assesses Tylochromis bangwelensis as Least Concern (assessed 16 February 2009 by T. Moelants, published 2010), with the population trend recorded as unknown. The assessment notes that overfishing — particularly the use of drawnets (seines) in the Luapula and Lake Mweru area of the broader system — poses a threat, but the species' wide occurrence across the Bangweulu wetland and its abundance in the fishery underpin the Least Concern listing. It carries no CITES or CMS listing and is rated of low fishing vulnerability with medium resilience. On the ground, however, the picture from the fishery is less reassuring: local studies describe the Bangweulu stocks as heavily exploited, with total catches declining under high fishing pressure, and caution that management should aim to stabilise rather than further increase the catch of an already-diminishing stock. As one of the most abundant and most targeted species in an artisanal fishery that supports many thousands of people, the hump-back bream sits at the intersection of food security and sustainable harvest — its long-term status depends less on any global threat than on how the Bangweulu and Luapula fisheries are managed, against a backdrop of intensifying effort and the swamp's strongly seasonal, flood-driven productivity.