Taxonomy & naming
Astyanax sincora was formally described by Burger, Carvalho, and Zanata in a 2019 paper published in Zootaxa (volume 4604, issue 2, pages 369–380). The type locality is the upper Paraguaçu River basin on the western side of Chapada Diamantina, in the state of Bahia, Brazil. Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) is the governing authority for the valid name; the species sits within the family Characidae.
The species belongs to the morphologically heterogeneous genus Astyanax Baird & Girard, 1854, one of the most speciose characid genera in the Neotropics, with well over 100 valid species distributed from the southern United States to Argentina. Burger et al. noted that A. sincora shares morphological characters with the Astyanax scabripinnis species complex, a grouping of small highland tetras from southeastern and central Brazil that has been subject to ongoing revision. As a recently described species, A. sincora has not yet been incorporated into comprehensive phylogenetic analyses of the genus.
Morphology
Astyanax sincora is a small, slender-bodied characid reaching a maximum recorded standard length of approximately 2.5 in. Like most Astyanax, it has the family's typical deep-bodied but laterally compressed profile, a forked caudal fin, an adipose fin, and a single row of teeth on each jaw. The species' distinguishing characters from congeners in the region were detailed in the original description by Burger et al. (2019).
Beyond the specific meristic and osteological characters that separate it from closely related species in the scabripinnis complex, the external appearance is typical of upland Astyanax: a silvery to translucent body, often with a lateral stripe of varying intensity, and a dark caudal spot at the base of the tail. Coloration in life may differ from preserved specimens; detailed colour notes from the original description provide the authoritative account. Data on secondary sexual dimorphism in the species are sparse in the available literature.
Habitat
Astyanax sincora is endemic to the upper Paraguaçu River basin on the western slopes of Serra do Sincorá, within the Chapada Diamantina highlands of western Bahia, Brazil. Collection sites are characterized as small creeks with muddy, stony, or sandy substrates, in a landscape shaped by a mix of cerrado-adjacent vegetation, grasslands, and the modified habitats of coffee plantations surrounding the watercourses.
FishBase records the species as benthopelagic in tropical freshwater, occurring at depths of 0–3 ft, consistent with the shallow creek habitat of its type locality. Serra do Sincorá is part of the larger Chapada Diamantina National Park area, a highland plateau known for high rates of fish endemism in its numerous isolated headwater drainages. The Paraguaçu River itself flows eastward into the Baía de Todos os Santos; the upper basin where this species occurs is hydrologically isolated from neighboring drainages by the highland topography.
Feeding
No dedicated feeding study exists for Astyanax sincora in the published literature captured in the research cache. Based on the ecology of the genus and the habitat — shallow, open-substrate creeks with surrounding grassland and plantation vegetation — the species is presumed to be an opportunistic omnivore in the manner typical of small-stream Astyanax, taking small invertebrates, insect larvae, fallen terrestrial arthropods, algae, and plant fragments.
Small upland Astyanax in general are known to exploit allochthonous inputs (material falling into the stream from bankside vegetation) as a significant food source, a feeding strategy well suited to the narrow, shaded creek habitats described for A. sincora. Aquarists keeping the species in captivity would find it accepts the standard range of small foods used for tetras — fine dry foods, frozen or live Daphnia, brine shrimp nauplii, and micro-worms — though no dedicated husbandry literature exists for this species specifically.
Mating
No observations of natural mating behavior have been published for Astyanax sincora. The genus Astyanax is broadly characterised as egg-scattering open spawners without parental care, and this is the expected reproductive strategy for A. sincora based on its phylogenetic placement and the ecology of the scabripinnis complex specifically.
In small-stream highland Astyanax, spawning is generally associated with fine-leaved vegetation, submerged roots, or stream substrate, where adhesive or semi-adhesive eggs are deposited and left to develop without guarding. Courtship behavior in the genus is typically brief and non-elaborate — a male pursues a gravid female through the water column — with spawning triggered by season, water temperature, or rainfall. Specific mating observations for this species remain unpublished to date.
Breeding
Dedicated breeding records for Astyanax sincora in captivity are not available in the published or hobbyist literature captured in the research cache. By analogy with other small Astyanax species, captive breeding is expected to follow the egg-scattering pattern: adults spawning over fine-leaved plants or a spawning mop, depositing small, adhesive eggs that receive no parental attention and are readily eaten by the adults if not removed.
Typical small-Astyanax breeding setup in captivity involves conditioning adults on a varied live and frozen diet, a modest rise in water temperature, and the presence of fine-leaved plant material such as Java moss as a spawning substrate. Eggs hatch within a few days at warm temperatures, and the fry initially require very small first foods before graduating to newly hatched brine shrimp. Because A. sincora was described only in 2019 and has a restricted natural range, it is not established in the wider ornamental trade, and breeding notes from hobbyists are absent from current sources.
In the aquarium
Astyanax sincora is not currently established in the ornamental fish trade and would be considered a scientific or specialist rarity if encountered outside its native range in Brazil. Should it become available, its ecology and size suggest care parameters broadly consistent with other small, upland Brazilian Astyanax: clean, well-oxygenated water in the mid-range tropical temperatures, moderate hardness reflecting its highland creek origin, and an open swimming space in a school of six or more individuals.
A biotope-style aquarium referencing the upper Paraguaçu headwaters — a sandy or fine-gravel substrate with smooth stones, sparse vegetation along the margins, and moderate flow — would be the most ecologically appropriate setting. As a small, active characid it should be compatible with similarly sized, peaceful tankmates. General Astyanax care principles (a varied diet, good filtration, a covered tank to prevent jumping) would apply. Data on specific care requirements for this species are data sparse pending hobbyist experience with the fish.
Conservation
Astyanax sincora has not been assessed by the IUCN Red List as of the date of this article; it carries a status of Not Evaluated (NE). The species was described only in 2019, and many recently described fishes from restricted localities take several years to reach formal conservation assessment.
The restricted geographic range — creeks draining the western slopes of Serra do Sincorá within the upper Paraguaçu basin — places A. sincora in a category of high inherent vulnerability. Its habitat includes streams bordered by coffee plantations and modified grasslands, which points to ongoing land-use pressure on the waterways. The Chapada Diamantina highlands as a whole are recognised for exceptional freshwater biodiversity and endemism, and hydrological isolation of headwater drainages means that local threats translate directly into species-level risk. No formal population estimates, range surveys, or threat assessments for A. sincora have been published to date.