Taxonomy & naming
Chrysobrycon guahibo was described in 2015 by Vanegas-Ríos, Urbano-Bonilla and Azpelicueta in the journal Ichthyological Exploration of Freshwaters (volume 26, number 2). The type locality is small drainages of the upper Guaviare River basin in Colombia, and the species is currently placed in the family Characidae (subfamily Stevardiinae in Eschmeyer's Catalog of Fishes, which records the valid name as Chrysobrycon guahibo Vanegas-Ríos, Urbano-Bonilla & Azpelicueta, 2015).
Chrysobrycon is a small genus of stevardiid characids distributed across Andean and sub-Andean drainages of South America. C. guahibo is notable for extending the known range of the genus into the Orinoco basin, making it the sole representative of Chrysobrycon in that major river system according to subsequent literature. Subsequent work through at least 2024–2025 (Eschmeyer's references 35265, 39298, 41166, 41972) has continued to treat it as a valid, distinct species.
Morphology
Chrysobrycon guahibo is a small, slender characid reaching approximately 2 in standard length, typical of the genus. Like other members of Chrysobrycon and the broader Stevardiinae it shows the elongate body form, moderate lateral compression, and the adipose fin present in most characids. Specific detailed meristic counts from the original description have not been reproduced in the sources available here, but the species was distinguished from its congeners by the authors on the basis of a combination of morphometric and meristic characters as well as colour-pattern details.
Detailed colour-pattern information in the hobbyist literature is sparse, reflecting the fish's rarity in trade. As a stevardiid, males may display secondary sexual characters on the anal-fin rays — a feature characteristic of the subfamily — but specific data on such structures for C. guahibo are not confirmed in the available cache.
Habitat
Chrysobrycon guahibo is known from small stream and drainage systems entering the upper Guaviare River basin, part of the Orinoco River system in Colombia. The type locality and associated drainages lie in Colombia's lowland savanna and transitional forest zones where the Guaviare originates along the eastern Andean foothills.
Water conditions at the type locality (Río Itilla) recorded in association with the original description include a temperature of 78 °F (78.3 °F), dissolved oxygen of 7.99 mg/L, and a slightly acidic pH, suggesting clear, well-oxygenated lowland streams in a forested or transitional environment. The species' distribution appears to be restricted to a small cluster of drainages, which is the primary basis for its IUCN Vulnerable assessment.
Feeding
No published data specific to the diet of Chrysobrycon guahibo in the wild are available in the sources reviewed. Members of Chrysobrycon and the broader Stevardiinae are generally understood to be omnivores feeding on small invertebrates, plant matter, and organic particles in their native streams, consistent with the feeding ecology of most small characids of similar body form.
In the aquarium, by analogy with related stevardiid characids, it would likely accept small live and frozen foods such as Daphnia, brine shrimp, and Cyclops, as well as fine-ground dried foods. Given the paucity of data, any more specific feeding claims would be speculative.
Mating
No specific observations on mating behaviour for Chrysobrycon guahibo are recorded in the available literature. Stevardiid characids — the subfamily to which C. guahibo belongs — include species with specialised male anal-fin hooks or other secondary sexual modifications involved in courtship, and some genera are known to have internal fertilisation or associated sperm transfer, though this varies across the subfamily.
For the genus Chrysobrycon in general, the reproductive biology remains incompletely described in the accessible literature. Egg-scattering spawning without parental care, as typical of most small characids, is the expected mode, but specific observations for this species are absent from the available cache.
Breeding
Chrysobrycon guahibo has not been reported from the ornamental fish trade and there are no published accounts of its captive breeding. Given the expectation of egg-scattering spawning typical of small characids, a breeding attempt would logically involve fine-leaved aquatic plants or spawning mops as spawning substrate for adhesive or semi-adhesive eggs, with the adults removed after spawning to prevent egg predation and no expectation of parental care.
The small body size (around 2 in SL) and preference for slightly acidic, well-oxygenated water at approximately 77–79 °F suggest broadly similar conditions to other small Amazonian–Orinocoan characids in captivity. All such information is extrapolated from the genus and subfamily context; no direct breeding data for this species exist in the literature reviewed.
In the aquarium
Chrysobrycon guahibo is not established in the ornamental fish trade and is essentially unknown in the aquarium hobby. No care accounts or reliable husbandry data exist in the available sources. The species is collected in remote Colombian drainages that are not major supply regions for the aquarium trade, and its small size and apparent rarity in the wild mean it is unlikely to appear in commerce under current conditions.
Should it ever become available, the water parameters from its type locality — approximately 77–79 °F (77–79 °F), slightly acidic pH, and well-oxygenated conditions — along with the small body size, suggest it would best be kept as a schooling species in a planted aquarium with gentle filtration and soft, slightly acidic to neutral water, consistent with the care requirements of small stevardiid and other small Orinocoan characids.
Conservation
Chrysobrycon guahibo is assessed as Vulnerable (VU) on the IUCN Red List, with an assessment date of 7 October 2020 referenced in the FishBase record. The listing reflects the species' very restricted distribution, confined to small drainages of the upper Guaviare River basin and a limited number of neighbouring stream systems within the Colombian Orinoco basin.
The Colombian Orinoco region faces ongoing pressures from land clearance, agricultural expansion, and alteration of stream habitats in the sub-Andean and lowland zones. A species known from only a small number of localised drainages is inherently vulnerable to localised habitat loss. Because C. guahibo is not established in the ornamental trade, there is no captive insurance population, and conservation of its wild habitat is the only existing safeguard for the species.