Taxonomy & naming
Cyphocharax stilbolepis was described by the American ichthyologist Richard P. Vari in 1992, part of his broader revision of the curimatid characins of the Neotropics. It belongs to the family Curimatidae — the toothless characins — within the order Characiformes, a family that sits alongside Serrasalmidae (piranhas, pacus and silver dollars) in the same broad characin radiation but occupies a very different ecological role as detritus- and algae-grazing fish rather than predators or fruit-eaters.
The genus Cyphocharax is large, with dozens of described species spread across South American river systems, and species-level identification within the genus rests on fine details of scale counts, fin-ray counts and body proportions that are difficult to assess without a specimen in hand. The specific epithet stilbolepis derives from Greek roots referring to the fish's bright, shining scales — a fitting description for a small silvery grazer whose only real ornament is its sheen.
Morphology
Cyphocharax stilbolepis is a small, laterally compressed characin with the typical curimatid body plan: a moderately deep, streamlined silver body, a small subterminal mouth adapted for grazing rather than biting, and no functional teeth in the jaws — the family name Curimatidae literally denotes this toothless condition. FishBase records a maximum size of 4.5 in total length, based on a holotype of 4.5 in standard length, making this a genuinely small fish by any characin standard, let alone next to the pacus and piranhas that dominate the popular image of the family Serrasalmidae.
As the epithet stilbolepis suggests, the species carries a notably bright, reflective silvery scale sheen, without the bold banding or bright fin colours seen in many tetras. Fin shape and count details are not documented in the available sources; like most curimatids it is likely to show little to no obvious external difference between the sexes.
Habitat
The species is known from the Tocantins and Xingu river basins of Brazil, with its type locality at Belo Monte on the Rio Xingu — both major, biodiverse tributary systems of the Amazon basin in north-central Brazil. As with other curimatids, it is a benthic-associated fish of flowing water, generally found over the substrate of river channels and tributary streams rather than in still floodplain lakes.
Specific water chemistry data for this species is not documented in the available sources, but the wider family Curimatidae is characterised as inhabiting rapid, well-oxygenated streams across a broad range from southern Costa Rica to northern Argentina, favouring a warm, mildly acidic-to-neutral, soft-to-moderately-hard environment. Strong current and good water quality appear to be a general requirement of the group rather than a still-water tolerance.
Feeding
Cyphocharax stilbolepis is a benthic detritivore and grazer, consistent with the toothless jaw and small downturned mouth typical of its genus and family. It feeds by sifting algae, biofilm and organic detritus from the substrate and from submerged surfaces, a lifestyle shared with its Curimatidae relatives and broadly with related genera such as Prochilodus and Semaprochilodus, though on a far smaller, non-migratory scale.
Related Cyphocharax species are documented as omnivorous-to-detritivorous grazers that, in aquarium conditions, accept high-quality pellets and flake foods with an algae content, along with live or frozen foods such as Mysis, mosquito larvae, daphnia, bloodworm and brine shrimp. Nothing in the available sources suggests C. stilbolepis departs from this pattern, but no aquarium-specific feeding data exists for the species itself.
Mating
No courtship or pairing behaviour specific to Cyphocharax stilbolepis is documented in the available sources. In related Cyphocharax and other small curimatid characins kept in aquaria, spawning is reported to be seasonal, with males displaying brighter colouration during the spawning period and courtship apparently cued by environmental triggers such as rainfall — a pattern common among South American floodplain characins whose reproduction tracks the wet season.
No external sexual dimorphism is documented for this species; the general absence of striking colour or fin differences between sexes in the genus makes visual sexing unreliable without further data.
Breeding
Breeding has not been documented for Cyphocharax stilbolepis specifically, and this species is not established in the aquarium trade or hobby breeding record. Drawing on the broader pattern reported for related Cyphocharax characins, the group breeds as open-water or plant-associated egg-scatterers: the female releases eggs over fine-leaved plants or spawning mops, the male fertilises them externally, and neither parent provides care — adults will consume the eggs if not separated from them. Reported hatching times in related species run roughly 24–36 hours depending on temperature, with eggs noted as light-sensitive.
This should be read as a description of the wider genus's typical mode, not a confirmed account for C. stilbolepis, which has no documented breeding record of its own. As a small, non-descript detritivore with no aquarium-trade presence, it is realistically not being bred in captivity at this time.
In the aquarium
Cyphocharax stilbolepis is not an established aquarium species — it does not appear in the trade, and no specific husbandry record exists for it. What follows is inferred from the broader family Curimatidae, to which it belongs, and should be treated as a general guide rather than species-specific guidance. Curimatids are current-loving, schooling fish that do best in a well-filtered aquarium with strong water movement and good oxygenation, mimicking the flowing streams the family inhabits; they are reported to be social, undemanding tankmates when kept in a group.
Water parameters for the family fall in a preferred range of roughly 73–82 °F and pH 6–7.5, in soft-to-moderately-hard water (2–15 dH). As a small, toothless detritivore under 4.5 in, C. stilbolepis poses none of the size, predation or plant-shredding concerns that apply to the pacus, wolf fish or silver dollars elsewhere in this atlas — if it were ever kept, it would be a modest, peaceful schooling addition to a river-biotope tank, not a fish requiring special caution.
Conservation
The IUCN Red List assesses Cyphocharax stilbolepis as Least Concern, with the most recent assessment dated 2022. This reflects a species that, while known from a comparatively restricted set of river basins (Tocantins and Xingu) rather than a continent-spanning range, is not currently flagged as facing significant population decline or listed threats.
The wider Xingu and Tocantins basins have faced substantial hydrological change from large dam projects in recent decades, which is a relevant long-term watch item for many species restricted to these basins, though no basin-specific threat data for C. stilbolepis itself is available in the sources consulted here. The species has no documented role in the aquarium trade or food fisheries.