Taxonomy & naming
Aphyocharax yekwanae was formally described by Philip Willink, Barry Chernoff, and Antonio Machado-Allison in 2003 in the journal Ichthyological Exploration of Freshwaters (volume 14, number 1). The description placed the species in the genus Aphyocharax — the bloodfin tetras — within the family Characidae, and the valid name as recorded in Eschmeyer's Catalog of Fishes is Aphyocharax yekwanae Willink, Chernoff & Machado-Allison, 2003.
The specific epithet yekwanae honours the Ye'kwana (also written Yekwana or Yecuana), the indigenous Carib-speaking people of the upper Caura and surrounding Guyana Shield highlands of Venezuela and Brazil. The type locality lies within their traditional territory. The species extends the known distribution of Aphyocharax to the northern slope of the Guyana Shield in the Orinoco drainage — a biogeographically significant addition — and is currently known only from the Río Caura basin.
Morphology
Aphyocharax yekwanae is a small, slender characid reaching a maximum recorded standard length of 2 in. The body is compressed and elongate in the typical bloodfin tetra mould. Meristic counts recorded in the original description include 9 dorsal soft rays, 15–17 anal soft rays, and 36–37 vertebrae — figures that place it squarely within the Aphyocharax range and distinguish it from several congeners.
The colour pattern follows the genus hallmark: the posterior body and tail region glow with vivid red pigmentation, concentrated in the anal-fin rays and the lower lobe of the caudal fin, extending toward the caudal fork. An adipose fin is present and is also pigmented red. The flanks are silvery with a faint lateral stripe. The intensity of red can vary with the fish's condition and lighting, but well-kept specimens display conspicuous scarlet that makes the species immediately recognisable as an Aphyocharax. Data on sexual dichromatism are sparse in published sources, though females in many congeners are slightly deeper-bodied when gravid.
Habitat
Aphyocharax yekwanae is endemic to the Río Caura, a major right-bank tributary of the Orinoco in Bolívar State, Venezuela. The Caura drains the eastern slopes of the Guyana Shield — ancient, nutrient-poor uplands of Precambrian rock — and its waters range from clear blackwaters in the upper reaches to moderately turbid conditions lower down, depending on season and substrate.
FishBase records the species as inhabiting the lee sides of islands and protected backwaters with sandy or rocky bottoms, in water characterised as clear to moderately turbid. It is classified as a tropical freshwater pelagic species, associated with the open water column rather than dense benthic cover. The Caura basin experiences pronounced wet and dry seasons that influence water levels, turbidity, and habitat connectivity; seasonal hydrology likely shapes the species' movement and spawning opportunities, though detailed field studies are lacking.
Feeding
No detailed dietary study specific to Aphyocharax yekwanae has been published, but the feeding ecology of the genus is well characterised from congeners such as A. alburnus and A. anisitsi. Bloodfin tetras are active, opportunistic feeders in the upper and middle water column, taking small aquatic invertebrates — insect larvae, small crustaceans, and zooplankton — as well as terrestrial insects that fall onto the water surface.
In captivity, Aphyocharax species are undemanding. Good-quality flake food, small granules, and frozen or live foods such as Daphnia, brine shrimp, and micro-worms are all accepted readily. As a small, fast-swimming species, A. yekwanae would be expected to feed in short, repeated bursts throughout the day rather than seeking out single large prey items.
Mating
Encyclopedia of Life records sexual reproduction for Aphyocharax yekwanae, consistent with the reproductive mode documented across the genus. Bloodfin tetras are egg-scattering open spawners; males pursue females actively and spawning occurs without pair-bonding or territory defence. In congeners, males display toward females with fin-spreading and body-quivering, and colour saturation — particularly the red of the anal and caudal fins — likely plays a role in mate assessment.
Spawning in wild populations is presumed to be seasonal, influenced by the flood pulse of the Orinoco system, though no fieldwork specific to A. yekwanae has documented trigger conditions in detail. In captivity, Aphyocharax species spawn readily once conditioned, with no special hormonal or environmental manipulation required beyond stable water conditions and good nutrition.
Breeding
Aphyocharax yekwanae follows the standard characid breeding mode: eggs are scattered among fine-leaved aquatic vegetation or spawning mops and are left entirely without parental care. The adults will consume eggs given the opportunity, so in a captive breeding programme the spawning medium should be removed to a separate rearing container as soon as eggs are deposited.
Eggs hatch within a few days at tropical temperatures, and the tiny fry are initially delicate, requiring very small first foods such as infusoria or commercial liquid fry food before graduating to newly hatched brine shrimp nauplii. Specific data on clutch size, incubation time, and fry development for this species are not documented in the literature available at the time of writing; published accounts of cognate species (A. alburnus, A. anisitsi) serve as the closest available analogue for husbandry planning.
In the aquarium
Aphyocharax yekwanae is essentially unknown in the aquarium hobby and is not in commercial trade at any significant scale; the genus is far better represented by the common Aphyocharax anisitsi (the Argentine bloodfin tetra). Should the Yekwana bloodfin become available, it would be expected to thrive under conditions appropriate to the genus: a temperature range in the low to mid 20s Celsius, slightly soft to moderately hard water, near-neutral pH, and good water quality with adequate oxygenation.
As a small, active schooling fish, it should be kept in groups of at least six to express natural behaviour and reduce timidity. A tank with a long open swimming area and fine-leaved planting at the margins suits Aphyocharax well. It would make an undemanding tankmate for similarly sized, peaceful community fish. The scarcity of the species in the trade reflects its restricted wild range and its IUCN Vulnerable listing rather than any particular difficulty in husbandry.
Conservation
Aphyocharax yekwanae is assessed as Vulnerable (VU) on the IUCN Red List under criteria B1ab(iii)+2ab(iii), assessed 18 August 2017. These criteria reflect a restricted extent of occurrence and area of occupancy, combined with observed or inferred decline in the quality of its habitat. The species is endemic to the Río Caura basin in Venezuela — a single river system — which means that any deterioration of that watershed represents a direct threat to the entire known population.
The Río Caura is among the least disturbed major Orinoco tributaries, and much of its basin falls within the Reserva Forestal de Imataca and adjacent protected areas; however, pressures including artisanal gold mining (with associated mercury contamination), deforestation in the catchment, and climate-driven changes in hydrology are documented concerns for the broader Caura ecosystem. The species' restricted range and single-basin endemism leave it with little resilience to range-wide disturbance. It is not known to be held in captivity in any conservation programme.