Taxonomy & naming
Parodon moreirai was described by Luiz F. S. Ingenito and Paulo A. Buckup in 2005 (Copeia 2005(4):765–771), part of a wave of species-level revision within Parodontidae that split what had once been treated as broader, wider-ranging "Parodon" populations into narrower, drainage-specific species. The type locality is Ribeirão do Salto, a small tributary stream near a wooden bridge at Delfim Moreira, Minas Gerais, Brazil (22°26'55"S, 45°20'47"W), in the upper Rio Grande drainage of the Paraná River basin; the holotype is held at the Museu Nacional, Rio de Janeiro (MNRJ 23583).
The genus Parodon sits in the family Parodontidae within Characiformes, a small family of fewer than 40 described species restricted to South America and often grouped loosely alongside Hemiodontidae and the wider characin assemblage in popular accounts, though the two families are not close relatives. The Catalog of Fishes (Eschmeyer, California Academy of Sciences) lists Parodon moreirai as a currently valid species (following Pavanelli's ongoing catalog review), with no synonyms or subsequent reclassification recorded. The species epithet honours a namesake associated with its description, per standard eponymous naming conventions in the genus; specific etymological documentation beyond the type description was not found in the sources consulted for this article.
Morphology
Parodon moreirai is a small, elongate, fusiform characin, reaching a maximum recorded standard length of 4.5 in — modest even by the standards of the "minor characins" grouped alongside it, and a fraction of the size reached by the pacus and dorado elsewhere in this broader assemblage. Like other Parodontidae, it carries the family's diagnostic "scrapetooth" head: a subterminal, downturned mouth positioned for grazing surfaces rather than the terminal, gape-forward mouth of a predatory characin, with a row of small, flattened, close-set teeth adapted to rasp algae and periphyton from hard substrate.
Detailed published description of body colouration and fin morphology specific to P. moreirai beyond the original taxonomic account was not found in the sources consulted; in general, Parodon species share a slender, torpedo-shaped body, a single dorsal fin set roughly at midbody, an adipose fin typical of characiforms, and a forked caudal fin suited to holding position in the flowing water the genus favours. No information on sexual dimorphism was located for this species.
Habitat
Parodon moreirai is known from the upper Rio Grande drainage within the Paraná River basin in Minas Gerais, southeastern Brazil — an upland, mountain-stream environment (the type locality sits in the Serra da Mantiqueira range) rather than the lowland floodplain habitat associated with many better-known Neotropical characins. FishBase categorises the species as a freshwater, pelagic fish, consistent with a stream-dwelling grazer that holds in the water column over rocky or gravel substrate in moving water.
Detailed water chemistry data specific to this species was not found in the sources consulted. As an upper-drainage, moderate-elevation stream species from the Serra da Mantiqueira, it is reasonable to infer clear, well-oxygenated, flowing water typical of that region, but no cited pH, hardness or temperature range exists for P. moreirai specifically, and this account does not assign figures beyond that inference.
Feeding
No species-specific diet study for Parodon moreirai was found in the sources consulted. However, its family membership is strongly informative: Parodontidae are the "scrapetooth" characins, and the genus's specialised, downturned mouth and comb-like dentition are built for grazing — rasping algae, biofilm and associated microinvertebrates from rock, wood and other hard surfaces in flowing water, the same general feeding strategy documented across related grazing characins such as the curimatas and hemiodontids that share this group's "quiet grazer" ecology.
No aquarium feeding data exists for this species, as it is not documented in the aquarium trade. Given the genus's grazing anatomy, a keeper attempting to house it would reasonably need to replicate an algae/biofilm-based diet with vegetable-forward foods and grazing opportunities on hardscape, but this is inference from family-level biology rather than a documented feeding regime for P. moreirai.
Mating
No courtship or pairing behaviour has been documented for Parodon moreirai in the sources consulted for this account. The species has not been reported in aquaculture or aquarium breeding literature, and no external sexual dimorphism has been described for it.
Breeding
Breeding biology for Parodon moreirai is not documented in the available literature. Unlike the true piranhas of this broader group (substrate nest-spawners with guarded eggs) or the pacus and Prochilodus (long-distance migratory spawners bred commercially with hormone induction), no reproductive mode — egg-scattering, nest-building or otherwise — has been recorded for this species or, in the sources consulted, characterised in detail for the genus Parodon as a whole. This account does not assign a breeding mode; data is sparse to nonexistent for this species.
In the aquarium
Parodon moreirai is not established in the aquarium hobby. No husbandry accounts, care sheets or trade records were found in the sources consulted, and the species' modest adult size (under 4.5 in) and specialised grazing mouth suggest it would need a stream-style setup — good water flow, oxygenation and hard surfaces to graze — rather than typical community-tank conditions, but this is inference from its morphology and family ecology, not documented practice.
The broader "Hemiodus & minor characins" group this species is filed under spans enormous variation in care needs, from schooling silver hemiodontids to giant, tank-outgrowing pacus and predatory dorado — none of that applies directly to P. moreirai, which by contrast appears to be a small, undemanding, unglamorous grazer largely absent from the trade. Anyone encountering this species would be working from taxonomic literature rather than established husbandry guidance.
Conservation
The IUCN Red List assessed Parodon moreirai as Least Concern in 2018. This reflects a species restricted to a specific upper-drainage stream system in the Paraná basin without documented major range-wide threats at the time of assessment, though — as with many narrowly distributed upland Brazilian stream fish — localised pressures from land-use change, water quality and habitat modification in the Serra da Mantiqueira region are the kind of long-term watch items relevant to small-range headwater species generally, even absent a specific published threat assessment for this species beyond its Red List category.
No information on trade collection or population trend specific to P. moreirai was found in the sources consulted; it does not appear to be a species under active harvest pressure for the aquarium trade.