Taxonomy & naming
Nannocharax wittei was described by the Belgian ichthyologist Max Poll in 1933, placing it in the genus Nannocharax within the family Distichodontidae — the African family that also holds the much larger, deep-bodied Distichodus and the algae-grazing citharinids. The genus Nannocharax comprises a large number of small, elongate, bottom-associated characins spread across Central and West African river systems, many of them described from single river basins and few of them well studied since their original description.
The Catalog of Fishes (Eschmeyer, California Academy of Sciences) governs the valid combination, and there is no indication in the available literature that wittei has been reassigned out of Nannocharax since Poll's original placement. Species-level taxonomy within Nannocharax remains active — related banded forms continue to be described from Central African basins, including recent additions from the Luapula River system in Zambia — which is a reminder that the boundaries of this genus, and the true range of any one species within it, are still being worked out.
Morphology
Nannocharax wittei is a small, slender, laterally compressed characin with a maximum recorded length of only 2 in total length, making it one of the smallest fish in the family Distichodontidae. Like other Nannocharax, it has a subterminal, downturned mouth suited to grazing surfaces rather than midwater feeding, and a body plan built for holding position against current on the riverbed rather than for open-water swimming.
Detailed published description of colour pattern and fin morphology specific to wittei is sparse; congeners in the genus typically show a dark lateral stripe or series of blotches along an otherwise pale-to-olive body, consistent with camouflage against rocky and gravel substrates. Sexual dimorphism has not been documented for this species (see "Mating").
Habitat
The species is known from Lake Calundo in the upper Zambezi basin (Angola) and from the upper Lualaba, part of the upper Congo River basin in the Democratic Republic of the Congo — a range spanning two of Central Africa's major drainages. Within that range it occupies flowing river sections over rocky substrate, a habitat type shared with other small Nannocharax species, which are typically found holding station in swift, well-oxygenated water rather than still backwaters.
Published water-chemistry data specific to wittei is not available; congener accounts (for example N. brevis) describe similarly structured habitat — fast-flowing stretches with rocky substrate and marginal vegetation providing cover. Given the upper Congo and upper Zambezi setting, warm, well-oxygenated, moderately soft water typical of Central African river systems is the reasonable expectation, but specific temperature and pH figures for this species are data sparse.
Feeding
Nannocharax wittei feeds on benthic invertebrates, grazing them from the rocky substrate it occupies — a diet consistent with its downturned mouth and bottom-hugging habit. Congener care notes (Nannocharax brevis) describe the genus as benthic invertebrate feeders that strongly prefer live or frozen foods such as bloodworm and Daphnia, with most individuals reluctant to take dry prepared foods.
In practical terms this makes the genus a specialist feeder rather than an easy omnivore: a keeper would need to offer small live or frozen invertebrate foods regularly rather than relying on flake or pellet, mirroring its natural diet of small invertebrates picked from stone and gravel in flowing water.
Mating
No courtship behaviour, spawning trigger, or sexual dimorphism has been documented for Nannocharax wittei in the available literature. This is consistent with the genus as a whole — Seriously Fish notes that breeding has not been established in captivity for Nannocharax species generally, and no aquarium or field spawning account for this species appears in the sources reviewed here. Given the absence of data, no mating description is offered beyond noting the gap.
Breeding
Breeding of Nannocharax wittei is not documented and, per genus-level accounts, has not been established in the aquarium hobby for Nannocharax at all. Related African distichodontids and citharinids are generally egg-scatterers with no parental care, but no confirmed spawning report — wild or captive — exists for this species specifically, so no breeding mode is asserted here beyond that likely family pattern. This is a species that, as far as the record shows, has simply never been bred in an aquarium.
In the aquarium
Nannocharax wittei is essentially absent from the aquarium trade — there is no established care history for this species specifically. Extrapolating cautiously from congeners such as N. brevis, a plant-rich tank of at least 10 US gal with strong flow, rocky and gravel substrate, and excellent oxygenation would suit its natural rocky-riverbed lifestyle, and live or frozen invertebrate foods (bloodworm, Daphnia) would likely be needed since the genus is reluctant to accept dry foods.
At under 2 in, this is a genuinely nano fish, and — unlike the trade's more famous, aggressive Distichodus or headline-grabbing piranhas — poses no size or aggression risk to anything. The honest caution for a prospective keeper is the reverse: this species is unstudied and effectively unavailable, so anyone encountering it would be working with a poorly documented import and should expect to research husbandry from congener accounts rather than species-specific guidance.
Conservation
Nannocharax wittei has not been formally assessed by the IUCN Red List; its status is Not Evaluated. This is common among small, single- or dual-basin Nannocharax species that receive little targeted survey effort relative to their range's remoteness in the upper Congo and upper Zambezi systems.
No population trend, threat assessment, or trade-pressure data exists for this species in the sources reviewed. Its narrow known range — Lake Calundo in Angola's upper Zambezi basin and the upper Lualaba in the DRC's upper Congo basin — would make it a candidate for concern if either system faced significant habitat pressure, but without an assessment this remains speculation rather than documented fact.