Taxonomy & naming
Hemibrycon yacopiae was described by César Román-Valencia and Doris K. Arcila-Mesa in 2010, as one of five new Hemibrycon species from the Río Magdalena basin in their revision published in the Revista de Biología Tropical (SciELO). The species is distinguished from the morphologically similar H. colombianus by a lower lateral-line scale count of 40–42 pored scales (versus 46–54 in H. colombianus) and fewer predorsal scales of 10–14 (versus 14–18). Eschmeyer's Catalog of Fishes (Catalog of Fishes, CAS) is the authority for the valid name Hemibrycon yacopiae Román-Valencia & Arcila-Mesa, 2010.
The genus Hemibrycon Günther, 1864 belongs to the family Characidae and encompasses numerous species of small to medium-sized characins distributed across Andean and sub-Andean river systems in South America. The group is ecologically associated with clear, fast-flowing streams and rivers, and species are frequently collected in benthopelagic zones over rocky or sandy substrates. Hemibrycon is known to be species-rich and incompletely described; molecular and morphological revisions continue to add new taxa from Andean drainages.
Morphology
Hemibrycon yacopiae is a moderately elongate, laterally compressed characid reaching 3.5 in standard length based on male or unsexed specimens recorded by FishBase. Like other members of the genus, it presents the typical hemibryconine body plan: a fusiform profile suited to life in flowing water, a single dorsal fin, a forked caudal fin, and an adipose fin.
The species is most readily separated from its congeners by meristic characters: 40–42 pored lateral-line scales and 10–14 predorsal scales, counts that fall distinctly below those of H. colombianus (46–54 and 14–18 respectively) and provide a reliable diagnostic. General coloration in Hemibrycon species tends toward silvery flanks with a dark lateral stripe running from the operculum to the caudal peduncle, but detailed pigmentation notes for H. yacopiae are not available in the accessible literature.
Habitat
The type locality of Hemibrycon yacopiae is Yacopi, in the department of Cundinamarca, Colombia, within the Magdalena River basin. FishBase records the habitat as benthopelagic freshwater, consistent with the genus's preference for the lower to mid-water column in river environments.
Water parameters recorded for the Yacopi area in the Magdalena drainage indicate a slightly alkaline, warm-water environment: pH approximately 7.3–7.6 and temperatures around 77 °F. The Magdalena drainage is one of South America's major river systems, rising in the Colombian Andes and flowing north to the Caribbean; the upper and mid-elevation tributaries where Hemibrycon species are found typically carry clear, well-oxygenated water over rocky or gravel substrates. The full extent of H. yacopiae's distribution within the Magdalena basin has not been comprehensively mapped.
Feeding
Specific dietary studies on Hemibrycon yacopiae are not documented in the available literature. Members of the genus Hemibrycon are generally considered opportunistic omnivores with an emphasis on invertebrates. In swift Andean streams, the diet of congeners typically includes aquatic insect larvae, terrestrial insects fallen to the water surface, small crustaceans, and some plant or algal material.
In captivity, fish of this size and body type in the family Characidae typically accept a varied diet of good-quality flake, micro-pellets, and frozen or live foods such as Daphnia and brine shrimp. As H. yacopiae is not established in the hobby, direct observations from aquarists are absent; care parallels likely apply to other swift-water characids of similar size.
Mating
No published data on the reproductive biology or mating behavior of Hemibrycon yacopiae are available. Based on the biology of the broader genus and family Characidae, the species is expected to be an egg-scattering open spawner with no parental care, a reproductive strategy nearly universal in hemibryconine and other small characids of Andean fast-water systems.
Congeners and ecologically similar characids from swift Andean rivers typically aggregate in pairs or small groups during spawning, releasing adhesive or semi-adhesive eggs that settle among fine gravel, plant material, or leaf litter. Courtship displays, if present, are likely brief and less elaborate than in lekking or nest-guarding species. Seasonal reproductive cues in Andean drainages often correspond to shifts in water level and temperature associated with wet-season rainfall.
Breeding
Hemibrycon yacopiae has not been bred in captivity as far as published records indicate, and the species is not established in the aquarium trade. Extrapolating from the reproductive biology of related Andean characids, breeding would be expected to follow the standard egg-scattering model: adhesive eggs scattered among fine-leaved plants or over substrate, with no parental care and adults best removed after spawning to prevent egg predation.
Incubation times and fry requirements are unknown for this species. By analogy with other small characids kept at similar temperatures (around 75–79 °F), hatching would likely occur within 24–72 hours, with free-swimming fry requiring infusoria or similarly fine first foods before accepting newly hatched brine shrimp. Any successful captive breeding would represent a first record of value to the scientific community.
In the aquarium
Hemibrycon yacopiae is not currently available in the aquarium hobby and is unknown in the trade. It has not been the subject of hobbyist keeping accounts. For the rare aquarist who might encounter this species through a specialist import or scientific collection, a setup approximating the natural habitat would be appropriate: a well-oxygenated aquarium with moderate to strong current, water temperature around 75–79 °F, pH in the neutral to mildly alkaline range (7.3–7.6), and clean, clear water maintained through regular water changes and efficient filtration.
As a schooling characid from a flowing-water environment, it would almost certainly fare best in groups of six or more individuals with sufficient swimming space. Open substrate zones and minimal decoration to reduce visual barriers would suit the active, riverine lifestyle of the genus. Diet would likely present few difficulties given the omnivorous habits of the family, but until captive husbandry experience accumulates, precise recommendations cannot be made.
Conservation
Hemibrycon yacopiae is assessed as Data Deficient (DD) on the IUCN Red List, with the assessment recorded as 10 October 2014. A Data Deficient listing indicates that insufficient information exists to evaluate the species' risk of extinction — not that it is necessarily secure. The Magdalena River basin faces ongoing pressures including deforestation of riparian zones, agricultural runoff, mining activities, and water extraction, all of which affect water quality and stream hydrology across the drainage.
The narrow type locality in Cundinamarca and the species' status as a recently described endemic heighten concern: if its range is genuinely restricted to a small area of the Magdalena catchment, it may be vulnerable to the habitat changes already documented across Colombia's Andean river systems. Systematic surveys to clarify the distribution, population size, and ecology of H. yacopiae would be a prerequisite for any meaningful reassessment of its conservation status.