Taxonomy & naming
Lebiasina yuruaniensis was described by Ardila Rodríguez in 2000, with the type locality in the Yuruani River system of Venezuela. The Yuruani drains the eastern Guiana Highlands and flows into the Río Caroní, itself a major left-bank tributary of the Orinoco. Eschmeyer's Catalog of Fishes (CAS) is the governing authority for the valid name; the specific epithet is a toponym directly derived from the type-locality river name.
The genus Lebiasina belongs to the family Lebiasinidae, a diverse Neotropical group that also contains the splashing tetras (Copella, Copeina) and the pencilfishes (Nannostomus). Within Lebiasinidae, Lebiasina is one of the larger genera, comprising small to medium-sized characins generally characterised by a laterally compressed body and, in many species, reddish or orange lateral banding. The placement of individual Lebiasina species has been revised periodically; the family as a whole is placed in the order Characiformes.
Morphology
As a member of Lebiasina, L. yuruaniensis is a small, laterally compressed characin typically under 4 in standard length. The genus is broadly characterised by an elongate body, relatively large scales, and in many species a conspicuous reddish or coppery lateral band running from the opercle to the caudal peduncle — a pattern shared with other Venezuelan Lebiasina and useful for field identification of the group at the genus level.
Detailed meristic and morphometric data specific to L. yuruaniensis are not widely available in the hobby literature. The original description by Ardila Rodríguez (2000) provides the diagnostic characters that distinguish this species from its congeners, including scale counts, fin-ray counts, and colour-pattern details. Sexual dimorphism in the genus tends toward females being more robust and deeper-bodied at maturity; males are typically more slender. Without access to the original description, precise counts cannot be reproduced here.
Habitat
The type locality is the Yuruani River, a stream system of the eastern Guiana Highlands in Venezuela. This region is characterised by tepui-influenced drainages — streams fed by the ancient sandstone tabletop mountains — which tend to carry soft, acidic, tannin-stained water. The Yuruani feeds into the Caroní basin, whose waters are notably clear and dark with dissolved organic acids, low in dissolved minerals, and warm year-round.
Lebiasina species more broadly favour shaded, slow to moderately flowing sections of streams, often among leaf litter, overhanging riparian vegetation, or submerged root masses. Water temperatures across the Guiana Highland foothills streams typically range from the low to mid 20s Celsius. The acidic, softwater character of these drainages is a feature shared by many endemics of the Guiana region and likely constrains the species' distribution to similar stream reaches.
Feeding
Data on the specific diet of L. yuruaniensis in the wild are not available in the accessible literature. Based on the feeding ecology of Lebiasina generally, the species is presumed to be an opportunistic omnivore, taking small invertebrates such as aquatic insect larvae, terrestrial insects that fall onto the water surface, small crustaceans, and supplementary plant or detrital material.
In captivity, related Lebiasina species adapt readily to standard aquarium foods — quality flake and micro-pellets, frozen bloodworm, Daphnia, and brine shrimp. The family Lebiasinidae includes surface-oriented foragers as well as mid-water feeders; given the species' stream habitat and the typical morphology of the genus, mid-water to surface feeding is most likely. A varied diet that includes live or frozen invertebrate foods is advisable for long-term condition.
Mating
No specific reproductive behaviour data have been published for L. yuruaniensis in the hobby or scientific literature. Within Lebiasinidae, reproductive strategies vary considerably: the splashing tetras (Copella arnoldi) are famous for depositing eggs above the waterline on overhanging leaves, while pencilfishes scatter adhesive eggs among fine-leaved plants. Lebiasina itself is understood to follow a more typical characiform pattern of egg-scattering with no parental care.
If the pattern of closely related species applies, males likely display to females with fin erection and lateral posturing, with spawning occurring among vegetation or over substrate. The absence of hobbyist breeding reports means the details of courtship and spawning site selection for this species are unknown.
Breeding
Lebiasina yuruaniensis has not been reported as bred in captivity in any widely available hobby source. Based on the reproductive biology of the genus and the broader family Lebiasinidae, it is expected to be an egg-scatterer that deposits small, adhesive eggs among fine-leaved vegetation or substrate; parental care is not expected in Lebiasina.
For aquarists who obtain specimens, a separate breeding tank with soft, slightly acidic water matching the Guiana Highland stream chemistry, dense fine-leaved plants or spawning mops, and subdued lighting would provide the most appropriate conditions for a conditioning and spawning attempt. Fry, if produced, would likely require microscopic first foods such as infusoria or commercial liquid fry food before advancing to freshly hatched brine shrimp nauplii. Given the sparse data, any successful captive breeding would itself be a meaningful contribution to knowledge of this species.
In the aquarium
Lebiasina yuruaniensis is essentially absent from mainstream aquarium commerce and is not described in standard hobby references. It would be considered a specialist or oddity fish if encountered, obtained perhaps through specialist importers dealing in South American species from the Guiana region or through hobbyist networks exchanging rare wild-type Lebiasinidae.
For any keeper lucky enough to source it, the water chemistry requirements would follow those of the Guiana Highland drainages: soft, acidic, warm water (approximately 72–81 °F, pH 5.5–7.0, low conductivity). A well-planted tank with leaf litter, subdued lighting, and gentle filtration would suit the species. Peaceful tankmates of comparable size — other Lebiasinidae, small Characidae from similar water types, or dwarf cichlids from Guiana streams — would be compatible. The species' small size and presumed peaceful nature make it suitable for a carefully curated biotope aquarium themed around tepui-drainage communities.
Conservation
Lebiasina yuruaniensis has not been evaluated by the IUCN Red List; no formal conservation assessment has been published. The absence of an assessment does not imply safety — many range-restricted Venezuelan stream endemics remain unevaluated simply because the volume of species in the region exceeds assessment capacity.
The Guiana Highland region of Venezuela, while still largely intact compared to more heavily developed parts of South America, faces increasing pressures from mining activity (particularly gold mining in the Caroní and Orinoco headwater regions), deforestation along stream margins, and the broader threats of climate change to highland stream ecosystems. A species with a type locality restricted to a single river system is inherently vulnerable to localised habitat degradation. Given the very limited information available on this species' range and population size, it merits attention from ichthyologists working in the region.