Taxonomy & naming
Chiloglanis marlieri was described by the Belgian ichthyologist Max Poll in 1952. It belongs to the family Mochokidae, the African squeakers and upside-down catfishes, and to the genus Chiloglanis — the suckermouth squeakers, a group of small rheophilic (current-loving) catfishes found across tropical Africa. The Catalog of Fishes (Eschmeyer, California Academy of Sciences) treats Chiloglanis marlieri as the valid name and current combination; there is no indication in available sources that it has ever sat in another genus.
The genus name Chiloglanis derives from Greek cheilos (lip) and glanis (an old name for a catfish), a direct reference to the group's defining feature: an oral sucker disc formed from thickened, fused lips used to grip rock in current. The species epithet marlieri honours a collector or researcher associated with the type material, a common naming convention in this genus. Chiloglanis is a large genus of many similarly built, hard-to-tell-apart species, and marlieri is one of the more range-restricted members, known only from its type locality.
Morphology
Chiloglanis marlieri is small even by the standards of its already diminutive genus, reaching a documented maximum of only 2 in total length. Like all suckermouth squeakers it has a flattened head and body — an adaptation for hugging rock faces in fast-flowing water — and a distinctive ventral mouth modified into a fleshy adhesive disc rather than the barbel-fringed jaws of most other catfish. Three pairs of barbels are still present around the head, but the sucker mouth itself is the diagnostic feature that separates Chiloglanis from other Mochokidae.
As in other members of the family, the skin is naked and scaleless, and the fish carries stiff, serrated spines at the leading edge of the dorsal and pectoral fins — the same locking mechanism that gives squeaker catfishes their name, used to wedge into crevices and to make an audible sound when handled. Colouration in the genus is typically a mottled grey-brown camouflage suited to a life spent flattened against current-swept rock, though detailed colour description for this specific species is not available in the cached sources.
Habitat
This species is endemic to the Ndakirwa River, a tributary of the Luhoho River within the upper Congo (Lualaba) drainage of the Democratic Republic of the Congo — a single known locality, placing it among the many narrowly distributed rheophilic catfishes of the Congo basin's tributary streams. It is listed as benthopelagic, living in and near the water column close to the substrate rather than buried in it.
As a sucker-mouthed Chiloglanis it almost certainly inhabits fast-flowing, well-oxygenated stream sections with a hard rock or cobble substrate, gripping the current-swept surfaces the way hillstream loaches and other rheophilic fishes do elsewhere in the world — though detailed habitat description beyond the type locality is not available. Water temperature at this equatorial DRC locality is inferred to run around 73–77 °F; specific pH and hardness data were not captured in available sources, so keepers should treat those figures as unconfirmed rather than assume soft blackwater conditions.
Feeding
Detailed dietary data for Chiloglanis marlieri specifically is sparse in the available literature. Suckermouth Chiloglanis as a genus are grazers, using their disc mouths to hold position on rock in current while rasping biofilm, algae and associated small invertebrates from the surface — closer in ecological role to an algae-grazing hillstream fish than to the nocturnal benthic scavenging typical of larger Mochokidae like Synodontis.
An aquarist keeping this genus should expect to offer a diet built around that grazing habit: algae wafers, blanched vegetables and biofilm-rich surfaces, supplemented with small sinking invertebrate foods, rather than relying on meaty pellet feeds alone. Because so little is documented for this exact species, any husbandry approach should be treated as an extrapolation from the genus rather than a confirmed protocol.
Mating
FishBase records Chiloglanis marlieri as oviparous with distinct pairing during breeding, but no further detail on courtship behaviour, spawning site selection or triggers is available in the cached sources. Data on mating behaviour for this species is sparse — it has essentially no presence in the aquarium hobby literature (PlanetCatfish's genus overview notes that species-level care and breeding detail for C. marlieri is thin), so almost everything known comes from the single taxonomic source rather than direct observation.
Breeding
There is no documented account of Chiloglanis marlieri breeding in captivity, and it does not appear to be established in the aquarium trade at all. The genus as a whole is rarely if ever bred by hobbyists; most Chiloglanis seen in collections are wild-caught incidental fish rather than deliberately targeted aquarium subjects, and this narrow-range, DD-status species is not known to be traded. Given the "distinct pairing" noted by FishBase, wild reproduction likely involves a female laying eggs that are guarded or attended at a fixed rock site rather than broadcast into open water, but this is inference from the genus and the terse taxonomic record, not a confirmed account for marlieri — it should not be presented as established fact.
In the aquarium
Chiloglanis marlieri is not a realistic aquarium prospect at present: it is not established in the hobby, has no confirmed trade presence, and almost nothing is documented about its captive husbandry. Its real, confirmed adult size is tiny — a maximum of 2 in TL — so this is emphatically not a fish that outgrows a small setup; the size trap that plagues so many catfish purchases simply does not apply here.
What can be said with confidence follows from its family and genus. Like all Mochokidae it is scaleless and naked-skinned, which means it would be more sensitive than scaled fish to copper-based medications and should be dosed conservatively if ever treated. It also carries the stiff, locking dorsal and pectoral spines typical of squeaker catfishes, which can snag in a net and jab the handler, so any specimen should be moved in a container rather than netted. As a rheophilic sucker-mouth grazer, a hypothetical aquarium would need to replicate strong current and biofilm-covered hard surfaces rather than the still, decor-heavy setups suited to typical community catfish — but this remains speculative extrapolation, not tested husbandry, given how little is recorded for the species.
Conservation
The IUCN Red List assesses Chiloglanis marlieri as Data Deficient. This reflects its status as a single-locality endemic of the Ndakirwa River, a tributary stream in a poorly surveyed part of the Congo basin, where there is not enough population, range or trend data to support a full threat assessment.
As with many narrow-range Congo basin stream fishes, the relevant long-term concerns are habitat degradation, deforestation, and water-quality pressure on its single known tributary rather than any documented population decline — but without further survey work, its true conservation status remains unknown. It is not known to be part of the aquarium trade, so collection pressure is not currently considered a factor.