Taxonomy & naming
Steindachnerina notograptos was described in 2009 by Lucinda and Vari in Copeia, based on a holotype of 3.5 in standard length collected from the Rio Palmas, part of the Rio Tocantins drainage in Tocantins state, central Brazil. It belongs to the family Curimatidae — a family of small to medium detritivorous characins, distinct from the toothed, predatory Serrasalmidae (piranhas and pacus) that dominate the popular image of Neotropical characins — within the order Characiformes. The genus Steindachnerina, honouring the Austrian ichthyologist Franz Steindachner, is one of the larger curimatid genera, with species distributed across South American river systems from the Magdalena basin in Colombia to the Río de la Plata in the south.
The species is distinguished from its congeners by an autapomorphy noted in the original description: a small, fleshy, lobulate structure paired on each side of the posterior limit of the medial fold of the buccopharyngeal complex, a throat-region feature tied to the family's specialised detritus-feeding apparatus. As with many recently described, single-river curimatids, S. notograptos has not been the subject of follow-up taxonomic or ecological work beyond its description, and the Catalog of Fishes lists it as a valid, accepted species under Steindachnerina — a placement this article follows without alteration.
Morphology
Steindachnerina notograptos is a small, laterally compressed, silvery characin consistent with the general curimatid body plan — an elongate, minnow-like shape built for steady shoaling swimming rather than the deep-bodied, ambush profile of a piranha or the barrel shape of a pacu. The species epithet notograptos derives from the Greek notos (back) and graptos (marked, written), referring to a pattern of dark spots along the dorsolateral body that distinguishes it from closely related Steindachnerina species.
The holotype measured 3.5 in standard length (roughly 3.5 in), and comparison with similarly sized congeners such as S. elegans (up to 5.5 in) and S. bimaculata (up to 7 in) suggests a mature adult size in the range of 3.5–6 in, though no independent size survey of S. notograptos itself has been published. Like other curimatids, it lacks the bladelike, interlocking jaw teeth of the piranhas and silver dollars in its order — its feeding structures are confined to the small pharyngeal and buccal specialisations used for scraping and processing detritus, described further below.
Habitat
The species is known only from its type locality, the Rio Palmas, a tributary within the Rio Tocantins drainage of central Brazil — a large, seasonally fluctuating river system that drains the Brazilian highlands north into the Amazon basin's eastern margin. No broader distributional survey has been published, so its range should be treated as apparently restricted to this drainage rather than assumed to be wider.
Specific water chemistry data for S. notograptos itself has not been documented in the available literature. Congeneric Steindachnerina species from comparable South American lowland and piedmont rivers are typically recorded from warm tropical water, roughly 75–81 °F, with soft, mildly acidic to neutral chemistry (around pH 5.5–6.8) — conditions broadly consistent with Rio Tocantins tributary habitat, though this should be read as a genus-level pattern rather than a confirmed measurement for this species.
Feeding
Steindachnerina notograptos is presumed, on the basis of its family and genus, to be a detritivore/grazer rather than a predator — curimatids as a group lack functional jaw teeth and instead use a specialised pharyngeal and buccal apparatus (including the fleshy lobulate structure diagnostic of this species) to process detritus, biofilm, algae and fine organic material scraped or sifted from submerged surfaces and sediment. This diet is characteristic of the whole Curimatidae family, in sharp contrast to the fin-nipping omnivory of true piranhas or the fruit-and-seed opportunism of pacus in the same order.
No aquarium or field feeding observations specific to S. notograptos have been published, so its exact dietary breadth — whether it also takes zooplankton or fine invertebrate material, as some congeners do — remains undocumented for this species specifically.
Mating
No courtship or spawning behaviour has been documented for Steindachnerina notograptos. The species is known to science only from its 2009 type description and a small number of comparative taxonomic notes; no aquaculture, aquarium, or field reproductive study has been published. Data on sexual dimorphism is likewise absent from the available record — this account does not assert a colour or fin difference between sexes because none has been documented.
Breeding
Breeding biology for Steindachnerina notograptos specifically is undocumented. Curimatids as a family are generally understood to be open-water or substrate egg-scatterers with no parental care, consistent with most small Neotropical characins, but this has not been confirmed for this species by any published study, and the species has never been bred — or even kept — in the aquarium hobby as far as the record shows. It is more honest to say plainly that breeding mode, fecundity and parental behaviour in S. notograptos are unknown than to assign it a mode by analogy alone.
In the aquarium
Steindachnerina notograptos has no documented presence in the aquarium trade. It does not appear in SeriouslyFish, mainstream hobbyist databases, or the trade literature, which is consistent with its status as a recently described (2009), single-drainage endemic with no known commercial collection or export history. Prospective keepers should not expect to find this species available, and any care guidance beyond the genus level (small, peaceable, detritus/biofilm-grazing shoaler needing warm, soft, well-planted or driftwood-furnished water, likely best kept in a group given the shoaling habits typical of curimatids) is inference from its family, not a documented account of the species itself.
Conservation
Steindachnerina notograptos has not been formally assessed by the IUCN Red List and carries no status; it is Not Evaluated. This is unsurprising for a small, recently described characin known from a single tributary of the Rio Tocantins with no commercial fishery or aquarium trade to draw conservation attention. Its apparently narrow known range within the Rio Tocantins drainage — a system subject to damming and hydrological alteration elsewhere in its course — would make it a reasonable candidate for future assessment, but no population trend, threat analysis or range-wide survey exists to support a status determination at this time.