Taxonomy & naming
Tylochromis jentinki was described by the Austrian ichthyologist Franz Steindachner in 1894, in the Notes from the Leyden Museum, as Paratilapia (Pelmatochromis) jentinki, on material from Buluma in Liberia. The lectotype, RMNH 5359 in the Naturalis collection at Leiden, was designated by Melanie Stiassny in her 1989 revision of the genus; a single paralectotype (NMW 58221) is held in Vienna. The species carries unusual taxonomic weight: when Charles Tate Regan erected the genus Tylochromis in 1920, he fixed Paratilapia (Pelmatochromis) jentinki as its type species by original designation, so jentinki anchors the name of the whole genus. Regan's 1920 genus, besides jentinki, took in Pelmatochromis polylepis Boulenger, 1900, and his revision the same year assigned six more species to it, splitting several out of Boulenger's old, catch-all Pelmatochromis lateralis; the genus stood at eight species until Jacques Daget added the Niger-system Tylochromis sudanensis in 1954. That slow trickle changed abruptly with Stiassny's monograph 'A taxonomic revision of the African genus Tylochromis' (Annales du Musée Royal de l'Afrique Centrale 258, 1989): nine new species in one paper nearly doubled the genus, from nine previously recognised species to eighteen, spread across West African coastal rivers, the Congo basin and the rift lakes (a total that further description work has since taken higher). She then used the genus, in 'Tylochromis, relationships and the phylogenetic status of the African Cichlidae' (American Museum Novitates 2993, 1990), to argue that the lineage sits near the base of the African cichlid tree, well outside the haplochromine and lamprologine assemblages of the Great Lakes. Older West African literature sometimes treated the Ivorian populations as the subspecies Tylochromis jentinki jentinki, but current usage (Catalog of Fishes; FishBase, following Lévêque, Paugy and Teugels) recognises a single, valid Tylochromis jentinki. West Africa holds only four Tylochromis species in total: coastal-river T. jentinki and T. intermedius, which can occur syntopically with the Sierra Leone endemic T. leonensis, and the more widely distributed, savannah-country T. sudanensis of the Niger, Cross and Wouri systems — jentinki's own range does not overlap sudanensis. The genus name combines Greek tylos, a callus or knob, with chromis, an old name for a perch-like fish — a reference to the swollen, thickened structures Regan saw in the head and pharyngeal apparatus. The epithet honours Dr Fredericus Anna Jentink (1844–1913), Director of the Dutch national zoological museum at Leiden, through whose institution Steindachner's type material passed.
Morphology
Tylochromis jentinki is a robust, deep-bodied and laterally compressed cichlid that grows large for the genus, reaching a maximum of about 10.5 in standard length; specimens of nearly 15.5 in fork length and over 1.3 kg have been recorded from the Ebrié Lagoon, though most fish taken in the fishery are far smaller, in the 4–7 in range. The build reads instantly as that of a benthic feeder: a steep forehead, large body scales, and a comparatively small, low-set mouth with fleshy lips, the upper edge of the lower jaw running horizontal when the mouth is closed. Fin counts run to 12–15 dorsal spines and 13–18 soft rays, with 3 anal spines and 7–10 anal soft rays over 31–32 vertebrae. Two diagnostic features separate it within the genus: there are three rows of scales between the anterior parts of the upper and lower lateral lines (Tylochromis carries the genus-typical paired lateral line), and in juveniles and mature females the lower-jaw teeth sit on a distinctly shelf-like, elevated process on the dentary. The defining hard-anatomy character of the genus as a whole is the lower pharyngeal jaw — heavy and, in jentinki, bearing the rounded crushing teeth that let it process hard-shelled prey. Colour is sober rather than showy: a uniform greyish to olive-green, palest below, with no bold barring or spotting. Sexual dimorphism is muted and most visible at spawning time. The genital papilla differs between the sexes — pointed in the male, more hemispherical and bearing two openings in the female — and ripening males develop brighter coloration and become more robust, while females remain a plain grey-green; outside the breeding season the sexes are difficult to tell apart on external appearance alone.
Habitat
The species occupies the coastal belt of West Africa, recorded in coastal rivers, estuaries and brackish lagoons from the Gambia through Senegal, Guinea-Bissau, Guinea, Sierra Leone, Liberia and Côte d'Ivoire to the Tano River in Ghana — the tropical Atlantic façade between roughly 14°N and 4°N. It is fundamentally an estuarine and lagoonal fish: FishBase classes it as preferring brackish water while also penetrating well upstream into fresh river reaches, and it tolerates a salinity gradient that few cichlids exploit so freely. The best-documented population, in the Ebrié Lagoon of Côte d'Ivoire, lives over soft lagoon bottoms in water that ran 1.5 to 4.2 parts per thousand salinity (mean about 3.2 ppt) and 81–87 °F across a two-year survey, with abundance shifting in step with the lagoon's salinity regime. As a benthopelagic, soft-sediment specialist it favours the muddy and sandy floors of lagoons, river mouths and the lower reaches of coastal streams rather than rocky or fast-flowing habitat. Depth in these shallow coastal systems is modest — the fishery works the upper few metres of the water column — and no great-depth occurrence is documented. Spawning and recruitment track the seasonal hydrology closely, with the reproductive season tied to the rising-water phase that follows the rains.
Feeding
Tylochromis jentinki is an opportunistic benthic macrophage — a sand-and-mud forager that grubs invertebrates out of soft sediment, with a pharyngeal mill to crush the hard-shelled fraction of its prey. Diet studies in the Ebrié Lagoon found it feeds chiefly on bottom invertebrates, with molluscs forming the dominant share (around 60% by index of relative importance) and insect larvae a substantial second (roughly a third), the balance made up of small crustaceans and incidental plant and detrital material. The single most-eaten item recorded by Amon-Kothias was the small estuarine bivalve Corbula trigona, a clam whose shell the fish's robust, molariform pharyngeal teeth are well suited to crack. This places jentinki firmly among the secondary consumers — organisms that live mainly on zooplankton and benthos — and FishBase estimates its trophic level at about 2.7, the value of an invertebrate-feeder rather than a piscivore. In the lagoon community it is itself prey: juveniles and small individuals are taken by flatfish and tarpon-like species, and adults by larger predators such as barracuda and threadfins. Functionally it fills the role its whole genus is built for — a roving, durophagous sifter of soft bottoms — rather than the algae-scraping, scale-biting or planktivorous niches of the famous rift-lake radiations.
Mating
Reproduction in Tylochromis jentinki follows the African mouthbrooding template rather than the biparental cave- or substrate-spawning of many other cichlids, and a key part of that template is that the species does not form a lasting pair bond — the male's role ends essentially at fertilization, and the female alone takes on the brood. The sexes are separate and, at maturity, distinguishable by the genital papilla, which is drawn to a point in the male and is more hemispherical with two openings in the female. As spawning approaches, ripening males put on brighter colour and greater body condition while females stay uniformly grey-green, the modest courtship dress of a fish whose parental investment is concentrated almost entirely in the mouthbrooding female. Maturity comes at about 6–6.5 in fork length, corresponding to roughly two years of age, with essentially the whole population mature by three years and around 8–8.5 in. Each female appears to spawn just once per breeding season, ripening a single batch of large oocytes for the event. Specific courtship and site-selection behaviour in the wild is poorly documented — a genuine gap for this and most of the genus — but the broad picture is of a roving benthic forager that pairs only transiently to spawn rather than holding a long-term territory.
Breeding
Tylochromis jentinki is a maternal mouthbrooder. After spawning, the female takes the fertilized eggs into her buccal cavity and incubates them there for an average of about 15 days, at the end of which she releases free-swimming fry of 0.5–1 in fork length — already vigorous and able to swim and feed. The eggs are large and yolky, averaging around 0.5 in along the long axis, and the clutch is correspondingly small: fecundity in the Ebrié Lagoon ran from about 110 to 420 eggs per female depending on her size, averaging roughly 1,100 eggs per kilogram of body weight. This is the classic mouthbrooder trade-off — a modest number of large, well-provisioned eggs and oral incubation buying high offspring survival in place of sheer numbers. In the lagoon the breeding season extends from August to February with a main spawning peak in November; spawning is induced by the seasonal rise in lagoon water level that follows the rains and the flood of the Comoé River (peaking October–November), and is associated with falling water temperature and salinity. This timing produces a roughly bimodal recruitment pattern, with a major pulse traceable to the late-year spawning and a minor secondary pulse. The species has never become a hobby breeding subject, so the captive reproductive cycle is essentially undocumented; what is known of its biology comes from the West African fisheries literature.
In the aquarium
Tylochromis jentinki is, for all practical purposes, not an aquarium fish. It is a large brackish-water food fish of West African lagoons and estuaries, harvested commercially rather than traded for the hobby, and it almost never appears in the ornamental market; nothing approaching a body of species-specific captive-keeping experience exists for it. What little anecdotal comment exists is genus-wide rather than about jentinki itself: Ad Konings has described Tylochromis in captivity as delicate yet lively, turning quarrelsome as they grow and needing a genuinely large tank to be kept together at size — a picture consistent with, though not proof of, how jentinki itself would behave. Any honest husbandry guidance therefore has to be inferred from the genus and from the species' own ecology, and the inferences all point to a demanding, specialist fish. Adults are big and deep-bodied — a maximum around 10.5 in SL, with exceptional individuals far larger — so they would need a long-footprint tank measured in metres, not a standard community aquarium. They are dedicated sand-sifters, so an open, deep bed of fine sand and a large area of clear bottom are essential; a rockwork-stuffed setup would suit them poorly. As a brackish, estuarine animal the species expects mildly saline to fresh, warm water (its lagoon habitat ran roughly 1.5–4.2 ppt salinity and 81–86 °F), and like its congeners it is a heavy feeder that kicks up detritus, so powerful filtration and excellent oxygenation would be needed; Tylochromis as a group are noted for poor tolerance of low oxygen. Diet would be straightforward in principle — a carnivore-leaning regime of frozen and live invertebrates, including shelled prey such as snails, plus quality sinking prepared foods, matching its natural mollusc- and insect-larva diet. In short, this is a fish to read about rather than to keep: an oversized, sediment-dependent brackish specialist with no track record in captivity, of interest for its biology rather than as an aquarium subject.
Conservation
The IUCN Red List assesses Tylochromis jentinki as Least Concern, assessed on 14 January 2020 (assessors Dankwa, Bousso and Lalèyè; published 2020), on the grounds that it occurs over a wide area of coastal rivers from the Gambia to Ghana and faces no major widespread threats. The population trend is recorded as unknown, and the only pressures flagged are local: drought and overfishing in particular parts of the range. It carries no CITES or CMS listing and is rated of low fishing vulnerability with high resilience. The species supports a real and valuable artisanal fishery — in Côte d'Ivoire's Ebrié Lagoon alone the seine fishery once landed on the order of 300 tonnes a year, the fish prized fresh and commanding a high price — and fisheries assessments there have generally found the stock under- to moderately exploited rather than overfished. As a salt-tolerant, wide-ranging habitat generalist it is far less exposed than the narrow-range endemics of the rift lakes. The honest framing is therefore that the fish itself is in no immediate danger, but the West African coastal lagoons and estuaries it depends on are under mounting pressure from pollution, altered freshwater inflow, drought and intensifying fishing — the backdrop against which its long-term status should be read.