Taxonomy & naming
Pyrrhulina eleanorae was described by Henry Weed Fowler in 1940 and placed in the genus Pyrrhulina, one of the splash tetras and pencilfish-relatives within the family Lebiasinidae. The original description was based on a specimen from Peru; the species remained obscure for decades, known only from that holotype, until it was rediscovered in 1994 in the Iquitos region of the lower Napo River drainage in northeastern Peru.
Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) is the governing authority for the valid name Pyrrhulina eleanorae Fowler, 1940. The genus Pyrrhulina belongs to the subfamily Pyrrhulininae within Lebiasinidae, a Neotropical family that also includes the pencilfishes (Nannostomus) and the remarkable splash tetra Copella arnoldi, famed for depositing eggs on overhanging leaves above the water surface. Within this family Pyrrhulina species are typically small, fusiform surface-oriented fishes of still and slow-moving Amazonian waters.
Morphology
Pyrrhulina eleanorae reaches a maximum recorded standard length of 3 in, placing it at the larger end of the genus. Like other Pyrrhulina it has a slender, cigar-shaped body with a notably upturned mouth suited to surface feeding, a single short dorsal fin set well back toward the posterior, and a rounded or slightly forked caudal fin.
The coloration of Pyrrhulina species is typically warm bronze to brown on the dorsal surface, with a prominent dark lateral stripe running from the snout through the eye to the base of the caudal fin, and a pale or silvery ventral surface. Detailed colour notes for P. eleanorae specifically are sparse in the literature; the genus pattern describes this species adequately — a cryptically marked, pencil-shaped surface fish whose relatively modest size and pattern blend with leaf litter and surface debris in shallow Amazonian backwaters.
Habitat
Pyrrhulina eleanorae is known from the lower Napo River and the Iquitos region of the upper Amazon basin in northeastern Peru. The Napo is a major left-bank tributary of the Amazon rising in Ecuador; its lower reaches near Iquitos flow through seasonally flooded terra firme forest, várzea floodplain, and associated still-water habitats including oxbow lakes, creek inlets, and flooded marginal vegetation.
FishBase records the species as benthopelagic in freshwater, with a temperature range of 75–82 °F reflecting the warm, equatorial lowland climate of the Amazonian plain. Pyrrhulina generally favours quiet, often heavily vegetated margins — the sort of shallow, still or barely-flowing black- or clear-water habitat where surface feeders can hover just below the film and intercept insects. Water in such habitats is typically soft and mildly acidic, consistent with the broader Amazonian terra firme profile, though measured water chemistry data for the exact collecting locality of P. eleanorae are not on record.
Feeding
Pyrrhulina eleanorae is a surface-oriented predator in the wild. The upturned mouth is adapted for intercepting prey at or just below the water surface: small insects, aquatic invertebrates, and fallen terrestrial insects form the bulk of the diet in nature. The genus name reflects this predatory character — pyrrhós, flame-coloured in Greek, but the genus as a whole is a group of active, quick-striking surface hunters.
In the aquarium P. eleanorae and its congeners accept live and frozen invertebrates readily — Daphnia, brine shrimp, bloodworm, and small insects. High-quality micro-pellets or small flake food floating at the surface is also taken, though a diet supplemented with live or frozen invertebrates improves condition and colour. These are not passive filter-feeders; they actively patrol the surface and will compete keenly for food, so care with tankmate selection and feeding technique matters.
Mating
Pyrrhulina species are egg-scatterers with minimal to no sustained parental care in most cases, differing in this respect from the closely related Copella arnoldi, which engages in elaborate terrestrial spawning on overhanging leaves with male water-splashing to keep eggs moist. In Pyrrhulina, spawning takes place in shallow, vegetated water; males court females near the surface among fine-leaved plants or submersed roots.
Male Pyrrhulina are territorial during the spawning period and may defend small patches of the water surface or marginal vegetation. Courtship involves displaying prominently to females, with the male's colour typically intensifying. Eggs are deposited in small batches among vegetation, usually attached or resting on plant leaves or substrate near the surface. Data on P. eleanorae specifically are limited given the species' rarity in both the wild and the hobby, and the following breeding section draws on the general Pyrrhulina model.
Breeding
Based on the Pyrrhulina genus model, P. eleanorae is presumed to deposit adhesive eggs in dense vegetation or among fine-leaved plants near the water surface. Parental care is reported as absent in most Pyrrhulina; the adults do not tend the eggs after spawning, and eggs and fry are left to develop unattended among the protective cover of vegetation.
Eggs hatch within a few days at tropical temperatures; the larvae are initially very small and require fine first foods such as infusoria or commercial liquid fry food before progressing to newly hatched brine shrimp. Because P. eleanorae remains rarely maintained or bred in the hobby — a consequence of its decades of obscurity and limited availability in the ornamental trade — detailed aquarium breeding records are sparse. Any hobbyist working with this species would be operating at the frontier of its husbandry documentation.
In the aquarium
Pyrrhulina eleanorae is rarely encountered in the ornamental fish trade and is primarily of interest to specialist keepers of Lebiasinidae or South American characoids. When available, it would be housed like other mid-sized Pyrrhulina: in a calm, well-planted aquarium with low surface agitation, soft and mildly acidic water (pH 6.0–7.0, temperature 75–82 °F), and floating or emergent vegetation that mimics the shallow Amazonian margins it inhabits.
As a surface fish it can be housed with calm bottom-dwelling species that occupy different water layers — small corydoras, dwarf cichlids, or other pencilfish-type tetras are natural companions. It should not be kept with larger, more aggressive fish that will outcompete it at the surface or stress it out of its feeding station. A secure lid is essential: Pyrrhulina are active surface fish and accomplished jumpers. Low lighting, tannin-stained water from leaf litter or peat, and a quiet environment bring out the best in the genus and reflect the still, forest-shaded backwaters where P. eleanorae is found.
Conservation
Pyrrhulina eleanorae is assessed as Least Concern (LC) on the IUCN Red List, the assessment having been made in 2014. The species is endemic to the Iquitos region of northeastern Peru and the lower Napo River drainage, an area that remains broadly intact in terms of the large Amazonian floodplain system it occupies. The Iquitos region, while a significant human settlement hub, sits within one of the largest intact freshwater ecosystems on Earth.
The species' rarity in collections through most of the twentieth century — known only from the holotype until 1994 — is more a reflection of limited ichthyological survey effort in the region than necessarily an indicator of rarity in nature. Nonetheless, its apparently restricted range within the lower Napo drainage, combined with ongoing pressures on Amazonian floodplain habitats from deforestation, agricultural runoff, and commercial fishing, warrants continued monitoring. The Least Concern status reflects current best evidence, but small-range endemics in active deforestation zones can shift categories quickly as survey data improve.