Taxonomy & naming
Tylochromis mylodon was described by the British ichthyologist Charles Tate Regan in 1920, in the same paper — 'A revision of the African cichlid fishes of the genus Tylochromis' (Annals and Magazine of Natural History, series 9, vol. 5) — in which he erected the genus itself. The type series came from Lukongolwa, on Lake Mweru in what is now the Democratic Republic of the Congo; the name has since been anchored to a lectotype in the Natural History Museum, London (BMNH 1920.5.26.165), with a single paralectotype (BMNH 1920.5.26.166), the lectotype designated by Melanie Stiassny in her 1989 monograph. That monograph — 'A taxonomic revision of the African genus Tylochromis (Labroidei, Cichlidae)' (Annales du Musée Royal de l'Afrique Centrale, 258: 1–161) — is the modern foundation of the genus, recognizing on the order of two dozen species and reassessing Regan's originals, Tylochromis mylodon among them. Stiassny went further in a companion paper ('Tylochromis, relationships and the phylogenetic status of the African Cichlidae', American Museum Novitates 2993, 1990), placing the whole genus near the base of the African cichlid tree, well outside the haplochromine and lamprologine assemblages that dominate the rift lakes. The species has never been split or synonymized under another name; it has stood as Tylochromis mylodon Regan, 1920 for over a century. Within the genus it belongs to the suite of Congo-basin species and is the textbook example of the lineage's crushing pharyngeal specialization.
Morphology
Tylochromis mylodon is a heavy, laterally compressed cichlid with the deep body, steep forehead, and small, low-set mouth that read instantly across the genus as a benthic forager rather than a midwater hunter — the 'hump-backed' of its English name. FishBase, following Stiassny (1989), gives a maximum size of 8.5 in standard length, with a maximum published weight near 964 g, making it a solidly built fish though modest by the standard of its giant Tanganyikan congener Tylochromis polylepis. The fins carry 13–14 dorsal spines and 14–15 soft rays, three anal spines and 7–8 anal soft rays, over 28 vertebrae. The single most diagnostic feature is hidden in the throat: an extremely robust lower pharyngeal jaw bearing mill-like molariform teeth that occupy at least two-thirds of the dentigerous surface — the most developed crushing mill in the genus, and the literal source of the species name. Other characters separating it from congeners are a lateral-line scale count of 38–43 (low, against the 54–59 of the many-scaled Tylochromis polylepis), 16–17 closely packed gill-rakers along the lower limb of the first arch, and an enlarged third pore of the mandibular laterosensory canal. Coloration is poorly documented from live fish — no FishBase photograph exists — but like its relatives it is a large-scaled, silvery-to-brassy benthic cichlid rather than a brightly patterned reef fish. Sexual dimorphism is not well described for the species; across the genus the sexes are similar, with females the brooding sex.
Habitat
Tylochromis mylodon is restricted to the upper Congo (Lualaba) basin, specifically the Lufira, Lake Mweru, and the lower and middle Luapula River, spanning the border of the Democratic Republic of the Congo and Zambia. It is a benthopelagic freshwater fish of soft-bottomed lake and connected-river habitats, classed by FishBase as benthopelagic — a bottom-oriented animal of the sandy and muddy shallows. The waters it inhabits are nothing like the deep, alkaline rift it superficially shares a genus with. Lake Mweru is a shallow, young floodplain lake on the Luapula–Congo, averaging only about 25 ft deep and ranging from roughly 10 ft in the shallow southeast to about 121 ft near the northwestern outlet to the Luvua, with annual water-level swings exceeding 10 ft and marked seasonal turbidity driven by Luapula discharge. Surface-water chemistry in the connected Luapula has been measured at pH roughly 6.2–8.4 and temperatures of about 65–82 °F, soft and far more variable than the buffered rift lakes. This is a warm, soft-to-circumneutral, turbid floodplain environment, and Tylochromis mylodon is one of its true Mweru–Luapula endemics — a benthic specialist of the lake bed and river channels rather than a wanderer of clear rocky shores. The species is noted for a marked intolerance of low oxygen, consistent with a fish of well-mixed shallow water rather than stagnant backwaters.
Feeding
Tylochromis mylodon is a benthic macrophage — a bottom forager that works soft sediment for invertebrates. Dietary study reports that it feeds mainly on insects and their larvae, with smaller quantities of crustaceans and molluscs, and FishBase estimates its trophic level near 3.3, squarely that of an invertebrate-feeder rather than a piscivore. What sets it apart from its congeners is the machinery rather than the menu: its enlarged molariform pharyngeal mill — the most developed in the genus — equips it to crush hard-shelled prey such as snails and small bivalves (durophagy) that softer-jawed relatives cannot exploit. In functional terms it sifts and grubs the bottom in the manner typical of Tylochromis, then processes hard items in the throat with that crushing plate. This makes it an ecological outsider in its own lake: where Mweru's haplochromine flock radiated into a spectrum of specialized niches, Tylochromis mylodon is a structurally conservative sand-and-mud generalist with a durophagous edge, sitting beside the radiation rather than within it. Its role in the community is that of a benthic invertebrate processor that can access the snail-and-clam resource of the lake bed.
Mating
The reproductive biology of Tylochromis mylodon follows the genus template, which is consistent and well established: it is a maternal mouthbrooder that does not form a pair bond. The male's role ends essentially at fertilization; there is no lasting partnership and no joint territory defended by a bonded pair, in contrast to the biparental cave- and substrate-spawners of the Tanganyikan lamprologines. This is the older, more generalized African mouthbrooding pattern shared with the haplochromines and tilapiines. Detailed courtship sequences, spawning-site selection, and the social structure of breeding aggregations have not been documented in the wild for this species specifically, and that gap is worth stating plainly rather than filling with conjecture. By analogy with better-studied congeners such as Tylochromis polylepis — whose juveniles are gregarious and whose adults become solitary, wandering benthic foragers — Tylochromis mylodon is likely a roving sand-dweller that defends a spawning site only transiently rather than holding a permanent territory. The crushing-jawed, hard-prey lifestyle does not alter the basic reproductive economy: a female courts, spawns, and then carries the brood alone.
Breeding
Tylochromis mylodon is a maternal mouthbrooder: after spawning, the female takes the fertilized eggs into her buccal cavity, where she incubates and guards them — and later the free-swimming fry — without help from the male. This is the genus-wide mode, reported for Tylochromis mylodon in both Stiassny's revision and the dietary/biological literature. Specific clutch counts for Tylochromis mylodon have not been published, but the closely studied congener Tylochromis polylepis offers a clear genus-typical figure: females have been observed carrying about 100 large eggs roughly 0.5 in in diameter — the classic mouthbrooder trade-off of a small clutch of big, yolk-rich eggs that hatch into well-developed young. Tylochromis mylodon, a somewhat smaller fish, would be expected to carry a comparable or modestly smaller brood. Parental care is entirely maternal and buccal: the female shelters eggs and larvae in her mouth through the vulnerable early stages and continues to offer refuge to the fry after they can swim. Wild spawning triggers, incubation duration, and the age at which the young become independent are not documented for this species, and no aquarium breeding account exists to fill the gap — it is a food fish, not a hobby subject, so the fine detail of its life cycle remains largely unstudied beyond the mode itself.
In the aquarium
Tylochromis mylodon is essentially absent from the aquarium hobby. In its native Mweru–Luapula range it is a commercial food fish — the 'Mweru hump-backed bream' of the local fishery — not an ornamental export, and there is no established body of keeping or captive-breeding experience for the species. Anyone considering it should treat the following as inference from the genus and the fish's biology rather than as a tested husbandry protocol.
This is a large, sediment-dependent, benthic cichlid that would demand a long tank with an open, deep sand bed — these are genuine sifters that work the substrate constantly, and a rockwork-stuffed setup would be both wrong for the animal and stressful to it. At 8.5 in and heavily built, a single adult or small group needs a footprint on the order of a six-foot tank, not a standard four-foot one. The two husbandry points the genus makes non-negotiable apply here directly: provide an open sand floor for natural sifting, and ensure strong filtration with excellent oxygenation, because Tylochromis are noted for a marked intolerance of low oxygen and an under-aerated or crowded tank is a real risk. Water should mirror the warm, soft-to-circumneutral, turbid floodplain conditions of Mweru rather than hard rift water — roughly 73–82 °F and pH around 6.0–7.8 — though the species' tolerance of variable river chemistry suggests it is not delicate about exact numbers so long as oxygen and cleanliness are maintained. Diet would be a carnivore/invertebrate regime: quality sinking pellets, frozen invertebrates, and the snails and hard-shelled foods its crushing pharyngeal mill is built to process. Temperament should be the genus's moderate, substrate-moving profile rather than outright nastiness, but scale and the need for a dedicated sand-floored, well-oxygenated system make it an advanced, specialist proposition — and in practice one almost no keeper will encounter.
Conservation
The IUCN Red List assesses Tylochromis mylodon as Least Concern, assessed on 16 February 2009 by Snoeks, Laleye, Moelants and Contreras-MacBeath, with the population trend listed as unknown. The species is widespread within the Mweru–Luapula–Lufira system and supports a commercial fishery; FishBase rates it as low in fishing vulnerability and high in resilience, the profile of a working food fish rather than a threatened narrow endemic. It carries no CITES or CMS listing. The honest framing is that the fish itself is not currently red-flagged, while the system it depends on is under genuine pressure. Lake Mweru is a shallow, productive floodplain lake exposed to heavy Luapula–Mweru fishing effort, sedimentation, and large natural water-level swings, and its fauna mixes true Mweru–Luapula endemics like Tylochromis mylodon with widespread Congo-basin species. The lake's young haplochromine cichlids are the products of a recent hybridization-seeded adaptive radiation (Meier et al. 2019), but Tylochromis mylodon is precisely not part of that flock — it is an ancient, structurally conservative lineage that long predates it. As a durophagous benthic endemic tied to the lake bed, its long-term status is bound to the health of Mweru's sediments, mollusc fauna, and oxygen regime rather than to any single immediate threat.