Taxonomy & naming
Chalceus guaporensis was described by Angela Zanata and Mônica Toledo-Piza in 2004 as part of a revision of the genus Chalceus, and its species epithet references the Rio Guaporé, the Bolivia-Brazil border river within its type distribution. It belongs to the genus Chalceus, a small group of silvery, deep-shouldered characins historically placed in or near the family Characidae; some classifications treat Chalceus as the sole genus of its own family, Chalceidae, a placement reflected in this genus's distinctive combination of large, metallic scales and a specialised, protrusible upper jaw unlike typical tetras.
Chalceus is one of several genera of fast-swimming, surface-oriented Neotropical characins — alongside the hemiodontids and other "minor characins" — that are frequently lumped together in the aquarium trade despite belonging to different families. The Catalog of Fishes (Eschmeyer, California Academy of Sciences) is the governing authority for the valid name and combination used here; no synonymy issue affecting this account is documented in the cache.
Morphology
Chalceus guaporensis has the classic Chalceus build: an elongated, laterally compressed body covered in large, brilliantly metallic scales that give the fish a polished, coin-like sheen — the genus name Chalceus derives from the Greek for "of bronze/copper." FishBase records a maximum size of 7 in standard length, a modest, genuinely manageable size compared to many of its relatives across the wider characin group covered in this atlas.
The caudal fin carries a vivid reddish-to-pinkish wash, a signature Chalceus field mark shared with congeners such as C. erythrurus and C. macrolepidotus, and the mouth is angled upward with a protrusible upper jaw well suited to picking prey from the surface film. Sexual dimorphism is not documented for this species in the available record.
Habitat
The species is known from the upper Rio Madeira drainage: the Rio Guaporé on the Bolivia-Brazil border, the Rio Madre de Dios in Peru, and associated tributaries of the upper Madeira in Brazil. FishBase classifies it as a tropical, freshwater, benthopelagic fish, meaning it ranges through the water column but is frequently found near the surface and along margins where terrestrial insects fall into the water.
Specific water chemistry data (temperature range, pH, hardness) is not captured in the cache for this species; as a lowland Amazonian-basin characin it can be expected to inhabit warm, tropical freshwater, but this account does not assign numeric parameters beyond what is documented.
Feeding
Chalceus guaporensis is documented as an insectivorous surface feeder, targeting ants and Lepidoptera larvae (caterpillars) that fall or are blown onto the water, along with beetles and crickets; the FishBase account for the genus also notes some plant material in the diet, consistent with a broadly opportunistic surface-feeding characin rather than a specialised predator.
This diet pattern places Chalceus guaporensis among the more omnivorous, insect-and-detritus-oriented characins covered in this atlas rather than with the large predatory genera such as Brycon or the dorado Salminus; it is not documented taking fish prey.
Mating
No courtship or spawning behaviour is documented for Chalceus guaporensis in the available record. Data sparse — this account does not speculate on pairing behaviour, triggers, or sexual dimorphism beyond what is stated above.
Breeding
Breeding biology for Chalceus guaporensis is not documented in the sources available for this account, and the species has no established record in aquaculture or the hobby to draw from. Given what is known of related open-water Neotropical characins, an egg-scattering strategy without parental care would not be surprising, but this is not confirmed for this species and should not be stated as fact. Prospective breeders should treat this as essentially unstudied territory rather than assume a specific mode.
In the aquarium
Chalceus guaporensis is rarely, if ever, seen in the ornamental trade — the cached record notes it turns up only occasionally, if at all, and most practical husbandry guidance available comes from its better-documented relative, the pinktail characin Chalceus erythrurus, kept under similar conditions by specialist importers. As a shoaling surface-dweller, it should be kept in a real group rather than alone or in pairs, since related Chalceus species become quarrelsome toward their own kind when kept too few.
The single most important husbandry note carried over from the genus is that these are exceptional jumpers — a tightly covered tank is not optional. General Chalceus care calls for a long, well-covered aquarium with open swimming space at the surface, since the fish patrols the upper water column; related species are reported as peaceful toward tankmates and not destructive to plants, unlike some other characins in this group. With a modest adult size around 6.5 in, it would not outgrow a reasonably large home aquarium, but its trade rarity means most of this is inference from the genus rather than species-specific experience.
Conservation
Chalceus guaporensis is assessed by the IUCN Red List as Least Concern. It is a range-restricted species known from the upper Rio Madeira drainage spanning Brazil, Bolivia and Peru, and there is no documented commercial fishery or significant trade pressure on the species — its near-absence from the aquarium trade means wild collection is not a meaningful threat. No specific localized pressures are noted in the available record; broader Amazonian-basin concerns such as damming and land-use change in the upper Madeira watershed are relevant long-term context but are not documented as active threats to this species specifically.