Taxonomy & naming
Nannocharax lineostriatus was described by the Belgian ichthyologist Max Poll in 1967, in his contribution to the ichthyological fauna of Angola published through the Companhia de Diamantes de Angola. Poll originally placed the species in the genus Hemigrammocharax, as Hemigrammocharax lineostriatus, a combination still occasionally seen in older hobby and museum literature. It was subsequently reclassified into Nannocharax, the genus of small African characins in the family Distichodontidae, and the Catalog of Fishes (Eschmeyer, California Academy of Sciences) governs that valid combination today.
Distichodontidae is an exclusively African family within Characiformes, uniting fish as different as the metre-scale, algae-grazing Distichodus with small, cryptic genera like Nannocharax and Neolebias. Nannocharax lineostriatus is one of many similarly patterned, poorly studied species in this genus, and confident field identification rests on the exact count and arrangement of the vertical bars crossing the dark lateral band, plus scale and vertebral counts from the original description, rather than on general appearance alone.
Morphology
The original description characterises Nannocharax lineostriatus by a dark, continuous stripe running from the snout to the base of the tail along the flank, crossed by a series of roughly nine to twelve narrow vertical black bars — the "lineo-striatus" pattern the species name describes. Poll's account gives scale and skeletal detail typical of a formal species description: about 34–35 scales along the longitudinal line, 6–9 pored scales along the lateral line proper, and 35–36 vertebrae.
As with many small Nannocharax, the body is elongate and only moderately compressed, with an underslung mouth suited to picking food from the substrate. Maximum size has not been reliably documented for this species in the sources available; related small Nannocharax species are typically nano-sized fish of a few centimetres, and this account will not assign a specific maximum length rather than guess one. No reliable sexual dimorphism has been documented for N. lineostriatus specifically, though in the related N. fasciatus, males are reported to be more colourful with a longer, thorn-like dorsal fin.
Habitat
Nannocharax lineostriatus is known from Angola, from the headwaters of the Kasai River (also spelled Cassai), a major left-bank tributary of the Congo River, and from related tributary systems draining into the upper Congo basin. Some accounts also associate lineostriatus-type forms with the Okavango and Kwanza river systems in the same region, though the taxonomic status of those populations relative to the nominate form is not resolved in the sources available here.
Within this range the species is reported from densely vegetated margins and wetland habitat typical of Congo headwater streams — shaded, structurally complex water over soft substrate, consistent with the genus's general habit of sheltering among plants and leaf litter rather than occupying open water.
Feeding
Detailed dietary data specific to Nannocharax lineostriatus is not available in the sources consulted here, but the genus as a whole feeds on benthic invertebrates in the wild, picking small prey items from the substrate and among plant roots and leaf litter. This fits the species' underslung mouth and bottom-oriented body.
In the aquarium, small Nannocharax are reported to accept small live and frozen foods such as bloodworm, Daphnia and mosquito larvae. There is no indication that this species takes plant matter or algae in any quantity, unlike its much larger relative Distichodus; it should be treated as a small invertebrate feeder rather than a herbivore.
Mating
No courtship or spawning behaviour specific to Nannocharax lineostriatus has been documented in the sources available for this account. General aquarium accounts of the genus note that in the related species N. fasciatus, males display a "parade" behaviour to females, using their more colourful, elongated dorsal fin. Whether N. lineostriatus shares this behaviour is not established here, and this account will not extend it to the species without direct evidence.
Breeding
Breeding of Nannocharax lineostriatus in captivity is not documented in the sources available for this account, and the species should be treated as effectively unbred in the hobby. Distichodontids in general — including the larger Distichodus and the citharinids — are egg-scattering species that are rarely, if ever, reproduced at home, and small Nannocharax appear to follow the same pattern: no established aquarium spawning protocol, no parental care behaviour recorded, and no commercial breeding to relieve pressure on wild populations. Anyone encountering this species in the trade should assume it is wild-collected rather than farmed.
In the aquarium
Nannocharax lineostriatus is essentially absent from mainstream aquarium literature, and specific care parameters for this species are not documented in the sources consulted here. Based on the genus and family, a heavily planted tank with shaded areas, soft leaf-litter substrate and gentle water movement — mimicking the vegetated Congo headwater habitat it comes from — is the reasonable starting point, alongside a diet of small live and frozen invertebrate foods rather than flake or vegetable-based foods.
Because almost nothing has been published on its temperament, social needs or realistic adult size, this is not a species to buy on impulse; a keeper considering it should treat it as an experimental, poorly documented fish and lean on general Nannocharax husbandry and close observation rather than on specific claims about this exact species.
Conservation
Nannocharax lineostriatus has not been assessed by the IUCN Red List and carries no formal conservation status; it is Not Evaluated. This is unsurprising for a small, range-restricted characin known mainly from Angolan Congo-basin headwaters and closely related tributary systems, an area with comparatively little targeted ichthyological survey work.
As with many similarly obscure single-region African characins, the absence of an assessment reflects a lack of data rather than evidence of security, and any conservation status implied here should be read as "unknown" rather than "safe."