Taxonomy & naming
Phenacogrammus stigmatura was described by Henry Weed Fowler in 1936. The genus Phenacogrammus belongs to the family Alestidae, the African tetras, a group distributed across sub-Saharan freshwater systems from the Nile to the Congo and Niger basins. The type locality is given within the Congo River system in what is now the Democratic Republic of the Congo. Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) is the governing authority for the valid name; the parenthetical authority reflects the original description under a name that has since been placed in Phenacogrammus.
Within Phenacogrammus the species sits alongside the well-known Congo tetra, Phenacogrammus interruptus, and a number of lesser-studied west-central African species. The genus is characterised by the combination of a generally robust alestid body plan, a forked tail, and in several species an elongate central caudal lobe in males — a feature that gives the type species its ornamental appeal. How P. stigmatura relates precisely to other members of the genus awaits a modern molecular phylogeny of the Alestidae.
Morphology
FishBase records Phenacogrammus stigmatura at a maximum standard length of 2 in, making it notably smaller than the Congo tetra (which reaches roughly 3 in SL in males). The body plan follows the alestid pattern: laterally compressed, with a forked caudal fin, a single dorsal fin, and an adipose fin. As a benthic-associated species, it likely shows proportions suited to life in the lower water column, though detailed morphometric data for this species are sparse in the accessible literature.
Coloration and any sexually dimorphic features — such as fin elongation in males — are not fully characterised in secondary sources available for this profile. Given the genus, males may show more developed finnage than females, as is common across Phenacogrammus, but this should be treated as provisional in the absence of confirmed observations.
Habitat
The species is recorded from the Congo Basin in the Democratic Republic of the Congo, with the type locality within the Congo River system. It is a freshwater fish, and FishBase codes it as having a benthic habitat association — meaning it spends time on or near the substrate rather than being exclusively a mid-water or surface schooler like many small characids.
The Congo Basin is the world's second-largest river drainage by discharge and encompasses an enormous variety of aquatic habitats, from the deep, fast main channel to slow blackwater tributaries, flooded forest, and swampy marginal waters. The precise ecological niche of P. stigmatura within this system — whether it favours forest streams, marginal swamps, or specific substrate types — is not documented in the sources available for this profile. Water chemistry across the Congo's forest tributaries is typically soft and slightly acidic, though main-channel water can be more neutral.
Feeding
No specific dietary data are available for Phenacogrammus stigmatura in the literature accessible here. By analogy with other small alestids and the broader genus, the species is presumed to be an opportunistic omnivore taking small invertebrates — insect larvae, microcrustaceans, and similar items — along with plant material and detritus. Benthic-associated species in this family often supplement a water-column insectivore diet with bottom-gleaned invertebrates and organic matter.
In an aquarium context, assuming comparable ecology to related Phenacogrammus species, the fish would likely accept a varied diet of small live and frozen foods such as Daphnia, bloodworm, and brine shrimp alongside quality dry foods. Data on feeding behaviour in captivity are absent from known sources.
Mating
Specific mating observations for Phenacogrammus stigmatura have not been reported in the accessible literature. Alestids in general, and the genus Phenacogrammus in particular, are egg-scattering open spawners: males court receptive females with fin displays and pursue them through vegetation or open water, culminating in brief spawning rushes during which eggs and sperm are released simultaneously. Eggs receive no parental attention and typically sink or adhere briefly to fine-leaved plants and substrate.
In the Congo tetra and related species, males develop elaborate finnage and intensified coloration as spawning condition cues. Whether P. stigmatura males display similarly elongated caudal lobes or other secondary sexual characters during courtship is not confirmed in sources available for this profile. Spawning in small alestids often peaks in the early morning hours, a pattern shared with many characid relatives.
Breeding
No captive breeding accounts are documented for Phenacogrammus stigmatura in the hobby literature, and the species is not known to be kept or bred in aquaria with any regularity. Based on the shared biology of the genus and family, breeding behaviour is expected to follow the alestid pattern: eggs scattered among fine-leaved plants or over the substrate, adhesive or semi-adhesive, with no parental care and adults that will consume their own eggs if not removed.
In related species breeding is typically triggered by water changes that simulate seasonal rainfall and temperature fluctuation. Incubation periods for small alestids at tropical temperatures commonly range from one to three days, with larvae becoming free-swimming shortly after hatching. All such details for P. stigmatura remain extrapolated from genus-level knowledge; direct captive records are absent.
In the aquarium
Phenacogrammus stigmatura is not an established aquarium fish. It does not appear in the hobby trade under any widely used common name, and no detailed husbandry profile has been published by the major hobbyist resources. Any aquarist encountering the species would be working largely from analogy with its better-documented congeners.
By comparison with other small Phenacogrammus, a soft, slightly acidic to neutral water chemistry reflecting Congo forest-stream conditions would be a reasonable starting point, with temperatures in the mid-to-upper 20s Celsius. As a small, presumably schooling characid, it would likely do best in a group in a well-planted aquarium with subdued lighting and dark substrate to encourage natural behaviour. The benthic habitat association recorded by FishBase suggests some time spent near the bottom, so a tank with open substrate areas alongside plant cover would suit it. Given the near-total absence of captive records, any keeper of this species would be contributing genuinely novel observations to the hobby literature.
Conservation
Phenacogrammus stigmatura has not been assessed by the IUCN Red List; it carries no formal conservation status at the time of writing. This reflects the broader pattern for many smaller, less commercially prominent Congo Basin fishes, which remain outside the scope of current assessment programmes despite the region's recognized importance as a global freshwater biodiversity hotspot.
The Congo Basin as a whole faces increasing pressure from deforestation, artisanal and commercial mining, agricultural expansion, and water extraction, all of which degrade tributary habitats. Without baseline population data or range surveys, the conservation trajectory of P. stigmatura is unknown. Its apparent obscurity in both the hobby and the scientific literature means that any collector, researcher, or aquarist with reliable distribution or natural history data for this species would be contributing meaningfully to what is currently a very thin record.