Taxonomy & naming
Chrysobrycon yoliae was described in 2014 by Vanegas-Ríos, Azpelicueta & Ortega. The type locality is an unnamed drainage flowing into the río Yucamia system, within the Río Ucayali basin of Peru. FishBase records the species with a maximum length of 2 in SL; the holotype measures approximately 2 in SL. Eschmeyer's Catalog of Fishes is the governing authority for the valid name.
The genus Chrysobrycon belongs to the tribe Stevardiini within Characidae, a group sometimes treated as the family Stevardiidae in older literature. The genus is defined by a suite of characters including male fin hooks, evidence of internal fertilisation inferred from comparative morphology, and the general small size and slender build common to its members. A 2024 revision by Vanegas-Ríos and colleagues describing the congener C. calamar provided a taxonomic key that confirmed diagnostic maxilla character states separating C. yoliae from related species within the genus.
Morphology
Chrysobrycon yoliae is a small, slender characid with a maximum recorded size of 2 in standard length (FishBase). The genus shows sexual dimorphism: males bear bony hooks on the fins, a feature seen across Stevardiini and associated with the group's internal fertilisation system. Females lack these hooks. Congeners in the genus cluster around 1.5 in SL in comparative material, placing C. yoliae among the smaller end of the Chrysobrycon radiation.
Detailed external descriptions of colouration in C. yoliae are not available in the literature consulted. Based on the genus and tribe, the body is presumed to be silvery and lightly built, typical of upper-Amazonian stream characids, but specific pigmentation patterns await a dedicated morphological account.
Habitat
Chrysobrycon yoliae is known from an unnamed drainage flowing into the río Yucamia system, a sub-tributary of the Río Ucayali basin in Peru. The Ucayali is one of the principal headwater systems of the Amazon River, draining the Andean foothills and associated lowlands of central Peru. The Yucamia sub-drainage lies within this lowland Amazonian zone and is characterised by warm, soft, slightly acidic to neutral tropical waters typical of upper Amazonian streams.
FishBase classifies the species under tropical water parameters. Beyond the basic drainage affiliation, detailed in-situ habitat observations — substrate type, depth range, canopy cover, water chemistry readings at the collection locality — have not been reported in the sources available. The species is endemic to Peru based on current records.
Feeding
No dietary data specific to Chrysobrycon yoliae have been published in the accessible literature. By analogy with its congeners and the broader Stevardiini clade, it is presumed to be a micropredator or generalist omnivore, taking small invertebrates, insect larvae, microcrustaceans, and fine organic matter in its stream habitat — consistent with the feeding ecology of small upper-Amazonian characids generally.
In captivity, similarly sized stevardiins are typically maintained on fine-grade prepared foods, small live or frozen invertebrates (Daphnia, Artemia nauplii, micro-worms), and occasional fine plant material. Whether C. yoliae has been kept long enough to document captive dietary responses is not recorded.
Mating
Chrysobrycon yoliae, like other members of the genus and tribe Stevardiini, is inferred to practice internal fertilisation. This is a derived condition within Characidae and sets Stevardiini apart from the majority of tetras, in which eggs and sperm are released freely into the water column. The male bony fin hooks — present in C. yoliae males — are functionally implicated in clasping females during sperm transfer, based on comparative studies across the tribe.
Spawning behaviour has not been directly observed and described for this species in the published record. Based on the internal-fertilisation reproductive mode of the genus, fertilised eggs are presumed to be released individually or in small batches after internal insemination, likely depositing among fine-leaved vegetation or submerged structure.
Breeding
No captive breeding records for Chrysobrycon yoliae have been documented in the hobby or scientific literature consulted. Based on the genus reproductive strategy — internal fertilisation followed by deposition of adhesive eggs, no parental care — the species would likely follow the general pattern inferred for Stevardiini: eggs scattered among aquatic vegetation after internal fertilisation, with incubation time and fry development parameters undescribed for this particular species.
Given its small size and remote, understudied type locality, C. yoliae has not entered the aquarium trade in any documented capacity, and practical breeding data remain absent.
In the aquarium
Chrysobrycon yoliae is not established in the aquarium hobby and is unlikely to be available through normal trade channels. Its collection locality — an unnamed stream in the río Yucamia sub-drainage of the Ucayali — is remote and rarely visited by commercial collectors, and the species has not appeared in hobbyist literature or trade databases.
Should the species become available, the care template for small upper-Amazonian stevardiins would apply: warm, soft, slightly acidic to neutral water in the range typical of Peruvian lowland streams, a well-planted aquarium with subdued lighting, fine-grade live and frozen foods, and maintenance in a small group. The internal fertilisation mode means that, unlike open-spawning tetras, females may already carry fertilised eggs when wild-caught. Husbandry details remain speculative in the absence of any reported captive experience.
Conservation
Chrysobrycon yoliae has not been formally assessed by the IUCN Red List. As of the cache date (June 2026), no assessment page exists for this species, and it carries no official conservation category. The species is known from a single unnamed drainage in the río Yucamia system of Peru — a restricted range in an area not intensively surveyed — which leaves its population size, trend, and vulnerability to habitat change entirely unknown.
The Ucayali basin faces ongoing pressures from deforestation, agricultural expansion, and hydrocarbon extraction in parts of its headwaters, and small-range endemics in understudied tributaries are among the species most at risk of being lost before they are properly known. Without a targeted survey of the type locality and adjacent drainages, the true range and population status of C. yoliae cannot be established.