Taxonomy & naming
Hemibrycon raqueliae was described by Román-Valencia and Arcila-Mesa in 2010 in a publication that simultaneously introduced four other new Hemibrycon species from the Magdalena basin of Colombia. The type locality is Tasajo creek, a tributary within the Río La Miel basin, itself a sub-drainage of the middle Río Magdalena. Eschmeyer's Catalog of Fishes governs the valid name; the authority is written without parentheses because the species was placed in Hemibrycon from its original description and has not been transferred.
Hemibrycon is a speciose genus of South American characids widespread in Andean and trans-Andean river systems from Venezuela south to Bolivia, with multiple species occurring in Colombia's major drainages. The Magdalena basin has proved particularly rich in undescribed diversity, and the 2010 revision demonstrated that Río La Miel, though a geographically compact drainage, harbours several distinct lineages. H. raqueliae is distinguished from its congeners by a combination of meristic counts and colour characters detailed in the original description. The specific epithet honours an individual named in the original paper; beyond the patronym, no published etymology is available.
Morphology
Hemibrycon raqueliae is a slender, laterally compressed characid reaching approximately 3.5 in standard length (3.5 in SL) based on the type series measured in the original description; FishBase records a maximum of 4 in SL. Like other members of the genus it displays the typical characid body plan: a fusiform shape, a small adipose fin between the dorsal and caudal, and a terminal mouth suited to capturing small invertebrates in fast-flowing water.
Colouration in preserved specimens follows the usual pattern for the genus — a silvery lateral band against a darker dorsum — but field notes from the type locality emphasise the clear-water montane stream setting rather than distinctive colour markings. Live colouration has not been formally documented in the published literature available at the time of this writing. Meristic data from the original description define the species, but those counts are not reproduced here because the primary text has not been independently verified against the printed tables.
Habitat
The species is known from the Tasajo creek system and broader Río La Miel basin in the Andean foothills of central Colombia, within the middle Río Magdalena drainage. Tasajo creek at the type locality measured 5 to 6 metres wide, with water temperatures around 71 °F, a pH of 7.3, and dissolved oxygen of 7.0 mg/L — conditions characteristic of cool, well-oxygenated montane tributaries. The substrate at the collection site consisted of stone, sand, and decaying organic material, a mosaic typical of shaded Andean foothill streams.
The Río La Miel basin sits at intermediate elevations on the western flank of the eastern Andes, where rapid changes in altitude compress a range of thermal and hydrological conditions into a short river length. The relatively cool water temperature and high dissolved oxygen concentration distinguish the habitat from lowland Magdalena conditions, and indicate that H. raqueliae is adapted to cooler, faster-moving water than many lowland characids.
Feeding
No published dietary study for Hemibrycon raqueliae is available at present. Genus-level data for Hemibrycon indicate that these are opportunistic carnivores and insectivores, taking aquatic invertebrates, terrestrial insects fallen onto the water surface, and small amounts of plant material. The well-oxygenated, stony-bottomed streams of the La Miel basin support abundant benthic invertebrate communities, which likely form the core of the diet.
In the aquarium, congeners accept live and frozen foods readily — Daphnia, brine shrimp, bloodworm, and small aquatic invertebrates — along with quality flake and small pellets. Any aquarium maintenance of H. raqueliae would sensibly begin with a protein-rich insectivore diet supplemented with prepared foods once the fish are settled.
Mating
No specific mating observations for Hemibrycon raqueliae have been published. Within Hemibrycon and the broader Stevardiinae and allied characid lineages, reproductive behaviour follows the egg-scattering open-water or substrate-spawning pattern: males pursue ripe females and the pair release eggs and sperm simultaneously into the water column or over fine-leaved vegetation, with the adhesive or semi-adhesive eggs settling among substrate or plant material.
Parental care is absent in Hemibrycon as far as is known; adults do not guard or tend eggs. Mature males in the genus typically develop small hooks on the anal-fin rays — a character common in the subtribe — which may function in maintaining close contact with the female during the spawning act. The extent to which this applies specifically to H. raqueliae awaits documented observation.
Breeding
Hemibrycon raqueliae has not, to the best of current knowledge, been bred in captivity and documented in the hobby literature. Breeding attempts with the species would logically begin by replicating the known parameters from the type locality: temperature around 70–72 °F, pH near 7.0–7.3, and high dissolved oxygen through vigorous surface agitation or an airstone.
By analogy with other Hemibrycon and small montane characids, spawning would be expected to occur over fine-leaved plants or a substrate of fine gravel, with eggs scattered in small batches and left unguarded. Removing adults after spawning and maintaining clean, well-oxygenated conditions in the rearing vessel would be the standard approach. Fry of small characids at hatching typically require infusoria or rotifers as first foods before accepting newly hatched brine shrimp. All of the above remains speculative until confirmed observations are published.
In the aquarium
Hemibrycon raqueliae is not currently available in the ornamental fish trade and is unknown in the hobby. Should it become available, its habitat data suggest the requirements of a cool-water montane characid: temperatures in the low 20s Celsius, neutral to slightly alkaline pH, and above all high dissolved oxygen maintained by good filtration and surface agitation. It would be unsuitable for a warm tropical community tank.
As a schooling characid, it would be kept best in a group of six or more in a species aquarium or alongside other cool-water fish of similar size and temperament. A tank with moderate flow, open swimming space, and some plant cover along the margins would approximate its native stream habitat. The data-sparse status of this fish means that any successful captive maintenance would itself constitute a contribution to knowledge of the species.
Conservation
Hemibrycon raqueliae is listed as Data Deficient (DD) by the IUCN, reflecting the absence of sufficient population data to make a reliable threat assessment rather than an indication that the species is secure. The Río La Miel basin, like much of the Colombian Andes, is subject to land-use pressures including agricultural expansion, deforestation of riparian zones, and water extraction, all of which can degrade the montane stream habitats these fish occupy.
The Magdalena basin as a whole supports an exceptional concentration of endemic freshwater fish, many of which face pressures from habitat modification and the introduction of non-native species. For H. raqueliae, basic information — population size, range extent beyond the type locality, reproductive rate — remains unpublished. Clarifying these gaps is a prerequisite for any meaningful conservation assessment. As one of several species described from the La Miel drainage in the 2010 revision, it represents part of a broader case for treating Magdalena montane tributaries as conservation priorities for Colombian freshwater biodiversity.