Taxonomy & naming
Astyanax saltor was described by H. Travassos in 1960 in the Brazilian journal Revista Brasileira de Biologia (volume 21, issue 1, pages 17–20), under the title "Notas ictiológicas. X. Astyanax saltor sp. n., do estado do Pará, Brasil." The type locality is the rio Cachimbo in Pará state, Brazil. Eschmeyer's Catalog of Fishes records the valid name as Astyanax saltor Travassos, 1960.
The species has been placed within the Astyanax bimaculatus species complex as discussed in the checklist literature (Lima et al. 2003; Bertaco & Garutti 2007 cited therein). Modern ichthyology treats Astyanax as a genus of the family Characidae, though the broader reclassification of some closely allied genera into the family Acestrorhamphidae has been noted in the literature — a reminder that the taxonomy of this group remains unsettled. The specific epithet saltor is Latin for "dancer" or "leaper," though documentation of Travassos's explicit rationale for the name is sparse in the available literature.
Morphology
Astyanax saltor is a small, slender-to-moderately-built characin with a maximum recorded standard length of 2.5 in. Like most members of the genus, it has the compact, laterally compressed body, terminal mouth, and adipose fin characteristic of the Characidae, along with the ctenoid scales and forked caudal fin typical of the group.
Detailed morphological data beyond size are sparse in the available literature for this species. On the basis of close congeners in the Astyanax bimaculatus complex, the fish is expected to show a silvery body with a dark lateral stripe and a humeral spot, the two dark marks that give the bimaculatus group its informal name. Sexual dimorphism is reported in congeners such as Astyanax aurocaudatus, where it manifests as differences in body depth and coloration between males and females; a similar pattern may apply to A. saltor, though no species-specific data are confirmed.
Habitat
The confirmed type locality of Astyanax saltor is the rio Cachimbo, a tributary system in Pará state, in the central Brazilian Amazon basin. This is the only rigorously verified locality; reports from Ceará in northeastern Brazil and from Peru remain unconfirmed and require voucher-based documentation before they can be accepted.
The rio Cachimbo drains tropical lowland rainforest and characteristically carries warm, soft, slightly acidic blackwater to clearwater conditions typical of many Amazonian tributaries. FishBase classifies the species as benthopelagic, meaning it occupies the lower to mid-water column and may be associated with bottom structure. No detailed habitat survey data for this species are available in the literature examined, and its microhabitat preferences — substrate type, vegetation, current — are not documented.
Feeding
No species-specific feeding study has been published for Astyanax saltor. On the basis of well-studied congeners — including the detailed work on A. aurocaudatus from the upper rio Cauca in Colombia — Astyanax species in this size range are broadly omnivorous, consuming aquatic and terrestrial insects, plant seeds, algae, and small crustaceans opportunistically. The diet tends to shift with season and prey availability, and many Astyanax species forage at the surface as well as in the water column.
In the aquarium, closely related small Astyanax accept a wide variety of foods: quality flake and micro-pellets, frozen invertebrates such as Daphnia, brine shrimp, and bloodworm, and occasional vegetable matter. Given the data-poor status of this species, specific feeding recommendations are extrapolated from the genus rather than from direct observation.
Mating
No mating behaviour has been described specifically for Astyanax saltor. The genus Astyanax is among the best-studied characin groups in terms of reproduction; the model species A. mexicanus is a well-documented egg-scattering open spawner in which females fed a high-fat conditioning diet for 10–14 days prior to spawning and then transferred to clean water will spawn readily with males. There is no parental care in this genus: eggs and larvae are left to fend for themselves after spawning.
In congeners including A. aurocaudatus, permanent sexual dichromatism has been documented, suggesting that visual signals play a role in mate recognition. Spawning in small Astyanax typically takes place among fine-leaved vegetation or over substrate, with eggs scattered non-adhesively or semi-adhesively, and it is assumed that A. saltor follows the same open-spawning, scatter-egg mode standard for the genus.
Breeding
Breeding details for Astyanax saltor specifically are not documented. The reproductive mode inferred for the species — egg-scattering open spawning over vegetation, no parental care — is standard for the family Characidae and well-attested across Astyanax. In aquarium settings, small Astyanax of this type typically spawn when a conditioned group of adults is moved to a bare or moss-furnished breeding tank and trigger by a partial water change.
Adhesive or semi-adhesive eggs are deposited among fine-leaved plants or synthetic spawning mops. The adults will consume eggs if left in the tank. At tropical temperatures (approximately 75–82 °F), incubation in comparable species takes on the order of 24–48 hours, with free-swimming fry appearing within a few days. First foods in similarly sized species are infusoria and micro-worm, followed by newly hatched brine shrimp. All of the above is extrapolated from related species; no captive breeding record for A. saltor is available in the sources examined.
In the aquarium
Astyanax saltor is essentially unknown in the ornamental trade and is not an aquarium fish in any practical sense. No commercial specimens appear to be available, and no hobbyist keeping or breeding records are found in the sources examined. The species is a scientific curiosity rather than a hobby animal at present.
Should specimens ever become available — for instance, through scientific collection or as bycatch in import shipments of Pará-region fish — the care framework for closely related small Astyanax would apply: a spacious tank with soft to moderately hard, warm water (approximately 75–82 °F), good filtration, and a mixed diet of prepared and live or frozen invertebrates. Small Astyanax are typically hardy, active, and schooling by nature, and do best kept in groups of six or more.
Conservation
Astyanax saltor is assessed as Data Deficient (DD) on the IUCN Red List, with the most recent published assessment dated 7 November 2018 (published 2022). The Data Deficient designation does not imply the species is secure; it reflects that insufficient information exists to make a reliable assessment of extinction risk. No population data, life-history information, or systematic survey results are available, and the known range — a single confirmed locality, the rio Cachimbo in Pará — is narrow.
Potential range extensions to Ceará and Peru require confirmation with voucher specimens before they can be incorporated into range assessments. The IUCN notes no conservation programs are in place in Brazil for this species and that it is not recorded from any protected area. Given the pace of habitat loss across the Brazilian Amazon and the lack of any monitoring data, the species' true status is unknown. The appropriate response is continued collection and taxonomic attention in the Cachimbo drainage, not an assumption of security.