Taxonomy & naming
Psectrogaster saguiru was described by the American ichthyologist Henry Weed Fowler in 1941. It belongs to the family Curimatidae — the curimatas, a large group of small-to-medium, toothless-jawed detritivorous characins — within the order Characiformes, the same order that contains the true piranhas, pacus and silver dollars of Serrasalmidae. The genus Psectrogaster is one of several curimatid genera (alongside Curimata, Cyphocharax and Steindachnerina, among others) distinguished mainly by fine anatomical details of the mouth, gill rakers and scale counts rather than by anything visually striking.
The Catalog of Fishes (Eschmeyer, California Academy of Sciences) is the governing authority for the valid name and combination; the cached FishBase and IUCN records used for this article both list the species as Psectrogaster saguiru (Fowler, 1941), and that combination is retained here without alteration.
Morphology
FishBase records a maximum length of 6.5 in standard length for Psectrogaster saguiru, describing it as a small fish for the order. Like other curimatids, it has a compact, laterally compressed, silvery body typical of an open-water-adjacent grazer, and — as is characteristic of the family — a small, toothless or near-toothless mouth adapted for sucking up sediment and biofilm rather than biting prey or plant matter. Detailed published measurements of body depth, fin formulae and colour pattern for this specific species were not available in the cached sources; readers should treat any finer anatomical description beyond size and general curimatid body plan as unconfirmed for now.
Habitat
Psectrogaster saguiru is native to South America, with FishBase placing its distribution in northeastern Brazil. It is described as a tropical freshwater species with a benthopelagic habit, meaning it moves through the water column close to the bottom rather than staying strictly on the substrate or strictly in open water — consistent with a fish that grazes organic material off submerged surfaces and sediment.
Specific river systems, water chemistry values (temperature, pH, hardness) and habitat structure were not detailed in the cached FishBase or IUCN records, and no aquarium-literature source was found for this species. Given the northeastern Brazilian setting, warm tropical conditions are a reasonable general expectation, but no specific figures can be cited here without risking fabrication.
Feeding
Curimatids as a family are detritivores and biofilm/algae grazers, feeding by sucking up fine organic sediment, decaying plant matter and the microbial film that grows on submerged surfaces, rather than hunting or browsing on living plant tissue. FishBase notes that food items are recorded for Psectrogaster saguiru but does not break the diet down further on the page consulted for this article, so the family-level pattern is the best available guide to its likely feeding ecology; no species-specific diet study was found in the cached sources.
Mating
No courtship, pairing or sexual-dimorphism information for Psectrogaster saguiru was found in the cached FishBase or IUCN records, and no aquarium or hobbyist source with breeding observations was located. Data sparse — nothing further can be stated here without guessing.
Breeding
Breeding biology for Psectrogaster saguiru is not documented in the cached sources — FishBase explicitly notes that breeding was not detailed on the page consulted. In general, small curimatids are assumed to be open-water or scatter-spawning egg-layers with no parental care, broadly similar to related characins such as the hemiodontids and other minor characins in this group, but that is a family-level inference, not a confirmed fact for this species, and it is not known to be bred in the aquarium hobby or commercially. Prospective keepers should treat its captive breeding as essentially unachieved and undocumented rather than assume any particular spawning mode.
In the aquarium
Psectrogaster saguiru is not an established aquarium species — no dedicated care guide, tank-size recommendation or husbandry account was found in the cached sources, and general aquarium-literature searches turned up nothing specific to it. Its modest adult size (6.5 in SL) and detritivorous, grazing lifestyle suggest it would behave, if kept, more like a peaceful, bottom-oriented shoaling grazer than anything resembling a piranha, but this is an inference from its family, not a documented care record. Anyone considering this species should treat husbandry information as effectively unavailable and proceed cautiously, sourcing further data before acquisition rather than relying on this article.
Conservation
The IUCN Red List assessed Psectrogaster saguiru as Least Concern, with an assessment dated 7 November 2018. FishBase's summary is consistent with this, also listing the species as LC. No specific threats, population trend, or conservation programme detail was available in the cached sources; the Least Concern rating implies a currently stable, non-threatened status within its northeastern Brazilian range, without indication of significant fishing or habitat pressure singled out for this species.