Taxonomy & naming
Phenacogaster lucenae was described in 2023 by Souza, Mattox, Vita, Ochoa, Melo & Oliveira. As a species described that recently, it is not yet indexed on FishBase and has not received a hobbyist profile in mainstream sources; the valid name is established by the original description and is recorded in Eschmeyer's Catalog of Fishes (CAS) as Phenacogaster lucenae Souza, Mattox, Vita, Ochoa, Melo & Oliveira, 2023.
The genus Phenacogaster Eigenmann, 1907 belongs to the family Characidae, the most species-rich family of freshwater fishes in the Neotropics. Phenacogaster is a moderately sized genus of small, laterally compressed, typically silvery characids found in lowland river systems across South America; the group is most diverse in Amazonian and Paraná drainages and is characterised by features of the humeral blotch, lateral-line squamation, and male fin-hook morphology that collectively define its limits relative to closely related small-tetra genera.
The specific epithet lucenae is a feminine patronym honouring Dr. Carlos Alberto Santos de Lucena of the Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, who has described or co-described numerous small Neotropical characids over several decades and is one of the central authorities on the group. The name acknowledges a major contributor to the taxonomy on which the description of P. lucenae itself rests.
Morphology
Phenacogaster lucenae is a small, slender-to-moderately-deep-bodied characid in the typical mould of the genus. Members of Phenacogaster are generally compact tetras reaching 1–2 in standard length at maturity, and P. lucenae falls within that range; precise maximum size data have not been published in sources accessible to this summary.
The genus is characterised by a combination of meristic and colour-pattern features: a moderate number of scales in the lateral series, a humeral blotch whose shape varies among species and is often diagnostic, and a caudal peduncle spot or stripe that connects with the caudal fin. The specific morphological characters distinguishing P. lucenae from its nearest congeners are defined in the original 2023 description; without access to the original paper's diagnosis and key, a detailed comparative account cannot be given here without risk of fabrication.
As in other Phenacogaster, males of P. lucenae likely bear small retrograde hooks on the rays of the anal and pelvic fins — a widespread secondary sexual character among male characids interpreted as facilitating close contact during spawning. Females are typically deeper-bodied. The general colour pattern expected for the genus is a silvery-translucent body with a dark lateral stripe or caudal spot, an adipose fin, and the small terminal mouth suited to invertebrate micropredation.
Habitat
The precise type locality of Phenacogaster lucenae is stated in the original 2023 description, which was not directly accessible for this summary. The genus as a whole ranges across lowland river systems of tropical and subtropical South America, with species recorded from the Amazon, Orinoco, Paraná-Paraguay, and São Francisco drainages and their tributaries. The multi-country author list of the original description (with contributors associated with Brazilian and other South American institutions) is consistent with a South American drainage type-locality.
Phenacogaster species typically inhabit marginal habitats and smaller watercourses: forest-edge streams, igarapés, river margins with reduced current, and floodplain pools with leaf-litter substrates and overhanging or aquatic vegetation. Water chemistry in these habitats is commonly soft, slightly acidic to neutral, and warm, reflecting the Amazon-basin norm of 73–82 °F and pH 5.5–7.0, though species associated with Cerrado or subtropical drainages may tolerate harder, more neutral water.
Data sparse: until the original description and any subsequent locality records become widely accessible, habitat details specific to P. lucenae cannot be confirmed beyond the genus-level baseline above.
Feeding
No published dietary data specific to Phenacogaster lucenae are available. The genus is composed of micropredators, and species-level diet studies are sparse across Phenacogaster generally. Gut-content analyses of congeners and other small characids from comparable forest-stream and river-margin habitats consistently show a diet dominated by small invertebrates: larval and adult aquatic insects, microcrustaceans (ostracods, copepods, small cladocerans), and terrestrial invertebrates falling or floating on the surface.
In an aquarium context, Phenacogaster tegatus — the congener with the most hobbyist documentation — accepts small live and frozen invertebrates (Artemia nauplii, Daphnia, micro-worm, grindal worm) readily, and transitions to high-quality micropellets and fine flake over time. This dietary profile is the best available proxy for P. lucenae pending specific data.
Mating
No observations of mating behaviour specific to Phenacogaster lucenae have been published. The species belongs to a clade of egg-scattering characids, and the expectation — consistent with all described Phenacogaster and the overwhelming majority of Neotropical small tetras — is of open-water or plant-associated scatter-spawning with no pair bond and no parental care.
Male characids in the genus bear retrograde fin hooks on the anal and pelvic fin rays, a morphological feature interpreted as facilitating close cloacal apposition during the spawning act and thereby improving fertilisation success. Typical Phenacogaster courtship, as documented for P. tegatus in captivity, involves lateral displays by males, brief chasing, and rapid side-by-side passes over fine-leaved vegetation or into open water during which eggs and milt are released simultaneously. Females are deeper-bodied when gravid, a reliable pre-spawning indicator for the group.
Breeding
Captive breeding of Phenacogaster lucenae has not been documented, and the species is essentially absent from the aquarium trade. As a 2023 description, it is too recent to have been systematically collected for the hobby, and no commercial captive-breeding programme is known.
Based on the biology of the genus, breeding would be expected to follow the standard small-tetra protocol: a conditioned group or a selected pair introduced to a heavily planted tank or a tank containing a synthetic spawning mop, with soft and slightly acidic water at 77–81 °F. Eggs are adhesive or semi-adhesive and would be deposited among fine-leaved vegetation or dropped onto the substrate; no parental care is given, and adults will consume eggs if not separated. Incubation for small characid eggs at these temperatures typically runs 24–48 hours, with free-swimming fry appearing a few days later. First foods for fry would be infusoria or commercial liquid fry food, advancing to Artemia nauplii within a week or two.
In the aquarium
Phenacogaster lucenae is not in the aquarium trade and has no established common name. Its 2023 description post-dates any meaningful hobby distribution, and it is unknown outside of museum collections and the researchers who described it.
For hobbyists who eventually encounter the species, the care template for Phenacogaster tegatus — the most commonly kept congener — is the appropriate starting point: a well-planted tank of at least 23.5 in, soft to moderately hard water at 72–82 °F and pH 6.0–7.5, a group of eight or more individuals (the genus is social and shows better behaviour and colouration in numbers), small live and frozen foods supplemented with high-quality micro-prepared foods, and peaceful tankmates of comparable size. A biotope-style setup with a dark substrate, leaf litter, and tannin-stained water would be consistent with the Amazonian forest-stream habitat profile of most Phenacogaster species and would likely suit P. lucenae well.
Conservation
Phenacogaster lucenae has not been assessed by the IUCN Red List. Described in 2023, it falls within the typical 3–5 year lag between description of a new species and the completion of a formal IUCN evaluation; its current status is Not Evaluated (NE).
No specific conservation data for the species are available. The conservation standing of any newly described small characid depends heavily on the size of its known range, the intactness of its habitat, and whether it is a genuinely restricted endemic or a more widespread but previously unrecognised species newly separated from a congener by revised taxonomy. Those details remain to be established for P. lucenae as collecting and taxonomic work in its home drainage proceeds.
The Amazon and associated drainage systems face ongoing pressures — deforestation, agricultural runoff, hydroelectric development, and artisanal mining — that collectively reduce the quality and connectivity of the forest-stream and river-margin habitats on which small characids depend. A formal IUCN assessment, ideally informed by field surveys of the type locality and surrounding areas, would be the appropriate next step for determining whether P. lucenae requires targeted conservation attention.