Taxonomy & naming
Nannocharax lineomaculatus was described by Blache and Miton in 1960 and placed in the genus Nannocharax, a large assemblage of small African characins within the family Distichodontidae — the same family that contains the much larger, deep-bodied Distichodus. The genus name combines the Greek nannos (dwarf) with charax, a classical name applied to characin-like fishes, an apt label for a genus whose members are consistently small relative to their distichodontid relatives. The species epithet lineomaculatus derives from Latin linea (line) and maculatus (spotted), referring to the row of small, lens-shaped (lenticular) spots that runs along the lateral line — the feature that gives the species its name and its main field mark.
Nannocharax is a large genus, with roughly thirty recognised species distributed across Central and West African river systems, and the Catalog of Fishes (Eschmeyer, California Academy of Sciences) is the reference for the currently accepted placement of lineomaculatus within it. Species-level identification within Nannocharax is difficult without close examination of spotting pattern, fin-ray counts and lateral-line scale counts, since many congeners share the same slender body plan and drab countershaded colouring.
Morphology
Nannocharax lineomaculatus has the typical Nannocharax body plan: an elongated, only mildly compressed body, a subterminal (underslung) mouth suited to picking food from surfaces, and a row of three to five lenticular (lens-shaped) spots along the lateral line that gives the species its name. As with its congeners, the fins are unremarkable — an adipose fin is present, as in other characins, and colouration runs to a pale, countershaded silver-to-olive base rather than the bright patterning seen in some other African characins.
Hard size data specific to lineomaculatus was not retrieved during research for this article; closely related congeners such as N. fasciatus and N. parvus are documented at roughly 2 in standard length, and it is reasonable to treat this as a general guide for lineomaculatus pending better species-specific data. This article does not assert a precise maximum length for lineomaculatus itself — treat any figure beyond "a small fish, on the order of a few centimetres" as an estimate from congeners rather than a confirmed measurement.
Habitat
Nannocharax as a genus is distributed across Central and West African river systems, with the wider genus recorded from the Congo basin and Luapula River drainage among other African waters; the specific river system(s) inhabited by N. lineomaculatus were not confirmed in the sources available for this article. Members of the genus are generally found in flowing, well-oxygenated stretches of river and stream, often over sand or fine gravel substrates where their underslung mouths let them graze the surface film and associated small invertebrates.
As with size, this article treats detailed habitat description for lineomaculatus specifically as unconfirmed and describes it in terms of the genus: a riverine, current-loving fish rather than a still-water species, consistent with the broader ecology of Nannocharax and the wider family Distichodontidae in African rivers such as the Congo.
Feeding
Nannocharax species, including close relatives of lineomaculatus, feed on small invertebrates picked from the substrate and surfaces rather than on plant matter — a different diet from the larger, herbivorous Distichodus in the same family. The underslung mouth typical of the genus is suited to this grazing, bottom-oriented feeding style.
In the aquarium, a diet of small live and frozen foods — daphnia, brine shrimp, micro-worms and similarly sized invertebrate foods, supplemented with high-quality small sinking pellets or flake — is the reasonable approach for this genus, mirroring what is documented for congeners. Specific feeding data for lineomaculatus itself is sparse, so this guidance is extrapolated from the genus rather than confirmed for the species.
Mating
No courtship or spawning behaviour specific to Nannocharax lineomaculatus was found in the sources available for this article. Distichodontids in general, including Nannocharax and the larger Distichodus, are not known for elaborate courtship displays, and this species should be assumed to follow that pattern absent better data — but that assumption is not a confirmed observation, and readers should treat any account of this species' courtship as unconfirmed.
Breeding
Nannocharax lineomaculatus has no documented aquarium or field breeding record in the sources consulted for this article. As with other Distichodontidae, African characins in this family group are egg-scatterers with no parental care, and Distichodus itself is notoriously difficult to spawn in captivity — but there is no confirmed breeding account for lineomaculatus specifically, and this species should be treated as effectively unbred in the hobby rather than assigned a confirmed breeding mode. Prospective breeders should expect very little published guidance and treat any attempt as exploratory.
In the aquarium
Nannocharax lineomaculatus is a poorly documented species in the aquarium trade, and it does not appear to be an established hobby staple; a keeper who encounters it should expect very limited husbandry information beyond what applies to the wider genus. Based on congeners such as N. fasciatus, a Nannocharax of this size can be kept in a modest aquarium (guidance for the closely related N. fasciatus cites a minimum of around 19.5 in tank length) furnished with sand or fine gravel, good water movement and strong oxygenation, reflecting its riverine origins.
As a small, likely peaceful bottom-and-midwater grazer, it is a reasonable candidate for a African river biotope community rather than a specimen fish, though tankmates should be chosen with its modest size in mind. Water should be kept warm, in the range suggested for the related N. fasciatus of roughly 72–81 °F, though this figure is drawn from a congener rather than confirmed for lineomaculatus itself. Because so little is published on this exact species, keepers should treat husbandry as a best-effort extrapolation from better-known Nannocharax relatives rather than settled fact.
Conservation
The IUCN Red List assesses Nannocharax lineomaculatus as Least Concern, though a specific assessment year was not retrieved during research for this article. A Least Concern rating for a narrow-range African riverine characin typically reflects a lack of evidence for population decline rather than detailed monitoring data, and as with many small, poorly studied Nannocharax species, the practical conservation picture is one of general data scarcity rather than known threat.
As with much of the genus, the species is not a significant presence in the aquarium trade, so collection pressure specific to lineomaculatus is not documented as a conservation concern. Broader pressures on African river systems — habitat degradation, deforestation-linked sedimentation and water-quality change — are relevant background context for small-range riverine characins generally, even though no species-specific threat has been documented for this fish.