Taxonomy & naming
Copella vilmae was described by the French ichthyologist Jacques Géry in 1963. Eschmeyer's Catalog of Fishes records the valid name as Copella vilmae Géry, 1963; the authority is not parenthetical, as the species was placed in Copella from the outset. The genus Copella belongs to the family Lebiasinidae — the pencil-fishes and splash tetras — which is distinguished from the superficially similar characid tetras by the absence of an adipose fin in most species and by details of jaw morphology.
Within Copella, the species is regarded as closely related to C. compta, another small Amazonian member of the genus with which it shares meristic values: eight dorsal rays and nine anal rays. The two can be distinguished by colour-pattern details, particularly in males. Copella as a genus is separated from the better-known Copeina by the presence of a distinct scales series pattern and by spawning biology.
Morphology
Copella vilmae is a slim, torpedo-shaped lebiasinid reaching approximately 2 in standard length in males and around 1.5 in in females — the pronounced size difference between sexes is typical of the genus. The body is laterally compressed and the mouth is directed slightly upward, consistent with a surface-feeding lifestyle. Dorsal-fin count is eight rays; anal-fin count is nine rays.
Sexual dimorphism is expressed in both size and colour patterning. Males carry an interrupted series of dark pigment along the midlateral scale row, producing a dashed longitudinal stripe effect. Females lack this pattern but show a small, distinct dark spot at the base of the upper caudal-fin lobe and a brownish band along the body. Both sexes lack the adipose fin that characterises many other characiform families. Base coloration is pale to silvery with brownish overtones, and the fins may show yellow or reddish tints in well-conditioned fish.
Habitat
Copella vilmae is known from the upper Amazon River system near Letícia, Colombia, close to the Colombia–Peru–Brazil border, and has also been recorded in Igarapé Préto in the upper Amazon drainage. The IUCN notes that the species occurs in pristine, well-preserved forest areas, a habitat condition that is closely tied to the blackwater streams and igarapés characteristic of this region.
The biotope is one of soft, highly acidic blackwater: water stained amber-brown by dissolved humus and tannins from leaf litter and decaying organic matter, with very low mineral content. Measured parameters from FishBase and hobby records give a pH of 4.5 to 5.2 and total hardness near zero (approximately 0.2 dH). Water temperature ranges from 73–77 °F. The species is surface-oriented and diurnal, occupying the upper water column in small groups among overhanging vegetation and submerged forest debris.
Feeding
Copella vilmae is a carnivore in the wild, feeding primarily at or near the water surface. The surface-oriented mouth and diurnal activity pattern point to a diet of small invertebrates — terrestrial and emergent insects, small aquatic invertebrates, and zooplankton — similar to other members of the genus.
In the aquarium it accepts a range of foods including small dried and prepared foods as well as fresh and frozen live foods. A diet that includes live or frozen daphnia, brine shrimp, or small insect-based foods will support best colour and condition. Because the species is a surface feeder, floating or slow-sinking foods are preferable to those that sink quickly past the zone where the fish naturally forage.
Mating
Copella vilmae is an open water egg-scatterer, spawning in free water rather than depositing eggs out of water as the more celebrated splash tetra Copella arnoldi does. Males court females actively, and the species' gregarious social structure means that courtship interactions occur within the group. The size and colour differences between sexes are presumed to play a role in mate recognition, with males displaying their longitudinal flank patterning to smaller, spot-marked females.
Brief records from hobbyist experience indicate spawning is very difficult to achieve in captivity, which limits the amount of observational detail available for this species. The general Copella pattern of group spawning with eggs deposited among fine-leaved plants or bottom substrate, followed by no parental care, is the most likely scenario.
Breeding
Copella vilmae is described as very hard to breed in captivity. As an open water egg-scatterer it deposits adhesive eggs into the water column rather than above the waterline, unlike C. arnoldi. No detailed captive breeding account has been widely published for this species, and it remains uncommon in the hobby.
For attempts, water chemistry must closely replicate the species' blackwater origins: very soft, highly acidic water (pH around 4.5 to 5.0, near-zero hardness) maintained with peat filtration or blackwater extract, at 75–77 °F. Fine-leaved plants or spawning mops placed in the upper third of the aquarium may serve as oviposition sites. Eggs and any fry should be removed from adults to a separate rearing vessel, as no parental care is given. First foods for fry would be infusoria or commercial liquid fry foods, followed by micro-nauplii.
In the aquarium
Copella vilmae is a peaceful, gregarious, surface-dwelling fish that should be kept in groups of eight or more individuals. A minimum aquarium volume of around 15 US gal is advised for a small group. Because it is a strong and agile jumper, a well-fitting, close-fitting cover is non-negotiable — escapes from open-topped or loosely lidded aquaria are a leading cause of loss in the hobby.
Water chemistry must be carefully maintained to match the species' extreme blackwater origins: pH 4.5 to 5.2, very low hardness (GH 2 to 5 dKH at most), temperature 73–77 °F. Peat filtration or the addition of blackwater extracts helps acidify and colour the water appropriately. The species is sensitive to abrupt changes in water parameters and to the presence of chemicals and medications, so water changes should be done gradually with matched-quality water. A biotope-style setup with a dark substrate, dried leaf litter, minimal current, and dim or diffused lighting suits it well and brings out natural behaviour. It is not a beginner's fish: stable soft-acid water chemistry and an experienced aquarist hand are prerequisites for long-term success.
Conservation
The IUCN assessed Copella vilmae as Least Concern in September 2020 (published 2023, version 2025-2), under assessment ID 159286744. The justification notes that despite the species' geographically restricted range — centred on the Amazon near Letícia, Colombia, and adjacent upper Amazon drainages in Brazil and Peru — it occurs within pristine, well-preserved forest that faces no identified immediate threats. Population trend is listed as unknown. The species is recorded in international ornamental aquarium trade at the national level, but this use is not considered a current threat.
The long-term security of the habitat remains the primary conservation consideration. The upper Amazon forest at the Colombia–Peru–Brazil border is among the more intact tropical forest regions in South America, but it is not without development and extraction pressures over longer time horizons. Because C. vilmae's distribution is limited and its exact population size is not quantified, continued monitoring of both the habitat and any trade volumes would be prudent.