Taxonomy & naming
Pseudocorynopoma heterandria was described by Carl H. Eigenmann in 1914. The valid name as recorded by Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) is Pseudocorynopoma heterandria Eigenmann, 1914; the authority is not parenthesised because the species was placed in Pseudocorynopoma at original description and has not been transferred.
The genus Pseudocorynopoma sits within the family Characidae and is distinguished from most characins by its reproductive strategy: females of the genus store sperm internally and can fertilise eggs after separation from the male — a trait documented in the genus by Burns et al. (1995) and shared with the more familiar congener Pseudocorynopoma doriae, the dragonfin tetra. P. heterandria is the less studied of the two species and is sometimes confused with P. doriae in older literature and in the trade.
Morphology
Pseudocorynopoma heterandria is a slender, moderately compressed characid reaching a maximum of approximately 2.5 in standard length, with males and undetermined individuals recorded at that size in FishBase data. The body form is typical of the genus: an elongated, somewhat streamlined profile suited to life in flowing water.
Fin and colour details are poorly documented compared to P. doriae, which is known for a fleshy, lobe-like appendage on the gill cover margin in males that mimics a small invertebrate and is thought to function in mating. Whether P. heterandria shares a similar structure has not been thoroughly described in readily accessible sources, and care should be taken not to project P. doriae morphology onto this species without direct evidence.
Habitat
The species inhabits coastal clearwater rivers in the states of São Paulo and Paraná in southeastern Brazil. These are benthopelagic, freshwater tropical streams — typically clear, with moderate flow and likely fine-leaved aquatic vegetation and submerged structure along margins.
Water chemistry data specific to P. heterandria are sparse. The congener P. doriae — collected from similar clearwater stream habitats in South America — is associated with temperatures of 68–75 °F, pH 6.0–7.5, and hardness up to about 20 dH. P. heterandria likely tolerates broadly similar conditions given the shared habitat type, though this inference should be treated cautiously in the absence of dedicated field data for this species.
Feeding
The trophic level for P. heterandria is recorded at 3.0 ± 0.4 in FishBase, placing it as a low-level carnivore or omnivore. At this trophic position the diet likely consists of small invertebrates — insect larvae, small crustaceans, and surface-fallen insects — consistent with the feeding habits of other small characids from similar clearwater stream habitats.
Detailed dietary studies specific to P. heterandria are not available in the literature accessible for this article. Aquarium observations of congeners suggest a willingness to accept a variety of small live and frozen foods alongside prepared diets, but husbandry data for P. heterandria itself remain sparse in the hobby.
Mating
Pseudocorynopoma heterandria is notable among characins for using internal insemination rather than the broadcast external fertilisation typical of egg-scattering tetras. This mode of reproduction was documented for the genus by Burns et al. (1995), making Pseudocorynopoma one of a small number of characid genera in which sperm transfer occurs internally. Females can store viable sperm, allowing fertilisation to occur after the pair has separated.
The precise courtship and mating behaviours of P. heterandria are not well described in available sources. In the related P. doriae, males possess a modified gill cover appendage thought to mimic prey and lure females close during courtship, but whether P. heterandria has a comparable structure or behavioural repertoire requires confirmation from direct study.
Breeding
Given the internal insemination documented for the genus, the reproductive biology of P. heterandria differs from that of typical egg-scattering tetras in an important respect: fertilisation is internal, though eggs are presumably still released into the environment. The finer details of spawning site, egg adhesion, clutch size, incubation period, and parental behaviour are not well documented for this species specifically.
Hobby breeding records for P. heterandria are rare, and most available guidance derives from experience with P. doriae. Aquarists keeping the species should expect broadly similar care requirements to the dragonfin tetra — a soft to moderately hard, slightly acidic to neutral water environment, fine-leaved plants or spawning substrate, and separation of eggs or fry from adults to improve survival. Data sparse — more dedicated records from keepers would meaningfully advance knowledge of this species.
In the aquarium
Pseudocorynopoma heterandria is rarely encountered in the hobby and is not commonly traded; most information available to aquarists is extrapolated from Pseudocorynopoma doriae care guides. Based on congener data and habitat origin, the species is likely best kept in a well-planted aquarium with clear, soft to moderately hard water at 68–75 °F and pH in the 6.0–7.5 range, with moderate flow and subdued to natural lighting.
As a benthopelagic stream characid from southeastern Brazil, it would likely benefit from a setup that replicates clearwater stream conditions — sandy or fine gravel substrate, driftwood, and abundant fine-leaved vegetation — and peaceful, similarly sized tankmates. The fishing vulnerability index is low (10/100 per FishBase), suggesting a species not under significant collecting pressure, but this also reflects how little it is targeted by the trade. Aquarists who do keep it should document care observations, as reliable hobby-level husbandry data for this species remain genuinely scarce.
Conservation
Pseudocorynopoma heterandria was assessed as Least Concern (LC) on the IUCN Red List, with the assessment published 7 November 2018. The LC listing reflects the absence of evidence for population decline meeting threatened thresholds at the time of assessment, not necessarily an abundance of population data.
The species is restricted to coastal clearwater drainages of São Paulo and Paraná in southeastern Brazil — a region subject to significant land use change, including deforestation, agricultural runoff, and urban expansion. Clearwater stream habitats in this part of Brazil face ongoing pressure, and the long-term status of species like P. heterandria depends on the condition of those catchments. Citizen-science records and targeted surveys in the São Paulo and Paraná coastal drainages would strengthen the data underpinning future assessments.