Taxonomy & naming
Nannocharax zebra was described by Andreas Dunz and Ulrich Schliewen in 2009 in Zootaxa, based on a holotype (MRAC 87-24-P-87, 1.5 in standard length) collected from the Cross River in Cameroon. It sits in the genus Nannocharax within the family Distichodontidae, the African characin family that also contains the large, deep-bodied Distichodus and the algae-grazing citharinids (treated by some authors as the separate family Citharinidae). The Catalog of Fishes (Eschmeyer, California Academy of Sciences) is the governing authority for the valid name and combination; nothing in the source record for this species suggests a taxonomic revision since its description.
Dunz & Schliewen distinguished N. zebra from its close relatives chiefly on the position of the anus relative to the anal fin: in N. zebra the anus-to-first-anal-fin-ray distance runs 2.2–3.7% of standard length, markedly shorter than the 4.2–14.2% seen in related Nannocharax species. The species epithet zebra refers directly to the vertical dark banding across the flanks, the fish's most obvious field character.
Morphology
Nannocharax zebra is a small, elongate, torpedo-shaped characin built for holding position in flowing water rather than for open-water cruising. Data are sparse beyond the type description, but the holotype measured 1.5 in standard length, and hobbyist sources place the maximum size at roughly 1.5–2 in SL, making this one of the smallest species in a genus that already runs small by characin standards.
The defining visual feature, as the name implies, is a series of vertical dark bars along the body, set against a paler ground colour — a pattern shared in general form with several other small Nannocharax but distinguished at the technical level by the anal-fin-to-anus spacing described above. Beyond size and banding, published morphological detail for this species is limited, and this account does not speculate beyond the type description and the available secondary sources.
Habitat
The species is known from the Cross River basin in Cameroon, with hobbyist sources additionally citing occurrence across parts of the Niger and Sanaga river systems in West and Central Africa. Like other small Nannocharax, it is associated with clear, oxygen-rich rivers carrying moderate-to-strong current — the kind of flowing, well-aerated water typical of the region's forest and savanna streams, rather than the still, tannin-stained backwaters associated with some other African characins.
Specific water chemistry data (temperature and pH range) were not captured in the available sources for this species; readers should treat any numeric water parameters offered elsewhere with caution until confirmed against a primary source, and should default to the general profile of warm, well-oxygenated, flowing Central/West African river water when in doubt.
Feeding
In the wild, Nannocharax zebra is reported to feed on benthic microorganisms and small insect larvae picked from the riverbed and rocky or sandy substrate, consistent with the grazing, bottom-oriented habit typical of small Nannocharax species. This is a fish that works the substrate rather than intercepting food in open water.
In captivity, sources report the species accepting brine shrimp nauplii, copepods, and fine powdered or granular foods — small live, frozen and prepared foods sized to its diminutive mouth. Given its size and benthic habit, food should reach the bottom rather than remain suspended in the water column.
Mating
No courtship behaviour specific to Nannocharax zebra was found in the available sources. Data are sparse for this species' reproductive biology beyond the reported spawning mode described below, and this account does not speculate about pairing, colour changes or courtship display in the absence of documented observations.
Breeding
Nannocharax zebra is reported as an egg-scatterer, depositing eggs among fine-leaved plants or moss in the wild — consistent with the general pattern for Distichodontidae and citharinids, which scatter eggs rather than guard a nest or brood. Like Distichodus and its relatives, this is a species that is rarely, if ever, bred in home aquaria; no aquarium-breeding reports were found in the available sources, and this account does not claim the species has an established captive-breeding protocol. Prospective keepers should treat any aquarium stock as most likely wild-collected or, at best, incidentally produced rather than deliberately farmed.
In the aquarium
Nannocharax zebra's small adult size (well under 2 in) means it is genuinely a nano species, but its ecology asks for more than a small footprint: sources recommend a tank of at least 39.5 in in length to give it the running current it needs, along with strong filtration and aeration to replicate the oxygen-rich, flowing water of its native rivers. A sandy substrate with smooth stones suits its bottom-grazing habit and lets it forage naturally.
As with other small riffle-dwelling characins, this is not a fish for a still, low-flow community tank — poor water movement and low oxygen are the more likely failure modes in captivity, not aggression or size. Given how little is documented about this species in the hobby, availability is likely limited and intermittent, and keepers should expect to source specific husbandry guidance from specialist African-characin keepers rather than general aquarium literature.
Conservation
Nannocharax zebra has not been formally assessed by the IUCN Red List and carries a status of Not Evaluated. This is unsurprising for a small, recently described, single-region West/Central African characin with a limited and lightly studied range; a Not Evaluated status reflects an absence of assessment rather than any evidence of stability or decline.
No specific conservation pressures on this species were found in the available sources. Given its association with clear, flowing river habitat in the Cross River and neighbouring basins, general pressures on Central/Central-West African freshwater systems — deforestation-linked siltation, water-quality change and habitat modification — are the plausible long-term watch items for a species with this ecology, though this account does not assert that any of them are currently documented as affecting N. zebra specifically.