Taxonomy & naming
Nannocharax micros was described by Henry Weed Fowler in 1936 from a holotype measuring 1 in standard length, making it one of the smallest formally described species in its genus. It sits in the genus Nannocharax, which the Catalog of Fishes (Eschmeyer, California Academy of Sciences) recognises as containing roughly 30 valid species of small African characins, within the family Distichodontidae — the same African family that includes the much larger, deeper-bodied Distichodus. The species epithet "micros" (see Etymology) directly reflects its tiny adult size relative to its relatives.
As with many small, range-restricted African characins described in the early-to-mid twentieth century, N. micros has not been the subject of a modern taxonomic revision or molecular study that would confirm its placement or clarify its relationship to similar-looking congeners. It should not be confused with the larger, banded species in the genus such as N. fasciatus, which are better documented in the FishBase and hobby literature; N. micros remains a poorly known, largely museum-record species.
Morphology
The only firm morphological data point available for Nannocharax micros is its holotype size: 1 in standard length, roughly 1 in. That places it among the smallest species in a genus that is already composed of small, elongate, torpedo-shaped characins rather than deep-bodied fish. Like other members of Nannocharax, it can be presumed to share the genus's general body plan — a slender, somewhat cylindrical body suited to life along riverbed substrates — but no published description of colour pattern, fin count, or other diagnostic features specific to this species is available in the sources consulted.
Given the absence of a detailed redescription, keepers and researchers should treat any claim about the adult size, colour, or fin morphology of N. micros beyond the 1 in holotype measurement with caution; data sparse is the honest characterisation of the species' morphology at this time.
Habitat
Nannocharax micros is a member of the Distichodontidae, a family restricted to Africa, and its congeners in Nannocharax are typically associated with small forest streams and river-margin habitats across the Congo basin and adjacent West and Central African drainages. However, no source consulted for this article documents the specific type locality, river system, or habitat conditions recorded for N. micros itself beyond its inclusion in the genus.
Without a confirmed locality or habitat description specific to this species, no meaningful statement can be made about its particular water body, substrate preference, or microhabitat. This is recorded here as a gap rather than filled with an assumption drawn from other Nannocharax species.
Feeding
No dietary study or field observation specific to Nannocharax micros appears in the sources available for this article. Small-bodied Nannocharax species as a genus are generally understood to feed on benthic invertebrates, detritus and algae along stream substrates, in keeping with the small-mouthed, bottom-oriented body plan typical of the genus, but this is a genus-level generalisation rather than a documented fact about N. micros specifically.
In the absence of species-specific feeding data, this article does not assign a definitive diet to N. micros beyond noting the genus-level pattern; any aquarium feeding recommendation would be extrapolation rather than documented fact.
Mating
No courtship, spawning behaviour, or sexual dimorphism has been documented for Nannocharax micros in the sources consulted. The species is known from a small number of preserved specimens rather than from field or aquarium observation, and nothing in the available literature describes how individuals pair, court, or select spawning sites.
This is an honest gap rather than an oversight: reproductive behaviour for this species is simply unrecorded, and no claim is made here about dimorphism or pairing behaviour.
Breeding
There is no record of Nannocharax micros being bred in captivity, and no field account of its spawning mode, egg type, or parental care exists in the sources available. Its relatives among the African distichodontids and citharinids — including the better-known Distichodus — are generally egg-scatterers with no parental care and are themselves rarely bred at home, which suggests N. micros is unlikely to be an aquarium-breeding candidate, but this is inference from family-level pattern, not a documented observation of this species.
Given the total absence of breeding data, this article makes no claim about a specific spawning mode for N. micros beyond noting that nothing has been recorded and that egg-scattering without parental care is the pattern typical of its closest relatives.
In the aquarium
Nannocharax micros does not appear to be an established aquarium species; no husbandry account, import record, or care guide was found among the sources consulted for this article. Its tiny recorded size — a holotype of only 1 in standard length — would in principle suit a nano setup among other small, peaceable African stream fish, but this is speculation based on size alone rather than any documented keeping experience.
Prospective keepers should treat this species as effectively unavailable and undocumented in the hobby. Anyone encountering fish sold under this name should verify identification carefully, since small, poorly known Nannocharax species are easily confused with one another and with similar-looking genera in the trade.
Conservation
Nannocharax micros is assessed by the IUCN Red List as Data Deficient, reflecting the absence of population data, distribution mapping, or threat assessment for the species. This status is consistent with a poorly collected, narrowly known African characin that has not been the subject of targeted field survey since its original description.
As with many Data Deficient African freshwater fishes, the general pressures facing small-stream habitats across Central and West Africa — deforestation, water-quality change and agricultural runoff — are plausible long-term concerns, but no source consulted ties a specific threat to N. micros itself. Its conservation status should be read as "unknown," not as evidence of either safety or decline.