Taxonomy & naming
Astyanax boliviensis was described in 2018 by Ruiz-C., Román-Valencia, Taphorn, Buckup, and Ortega in the European Journal of Taxonomy (DOI: 10.5852/ejt.2018.402). The type series was collected from the Madidi and Mamoré rivers in Bolivia, and the name boliviensis — from the Latin adjectival form of Bolivia — directly references the country of origin of the type material. Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) recognises the valid name as Astyanax boliviensis Ruiz-C., Román-Valencia, Taphorn, Buckup & Ortega, 2018.
The species belongs to the orthodus species-group of Astyanax, a large Neotropical genus that spans most of South and Central America and currently comprises well over one hundred valid species. The 2018 description compared boliviensis morphologically against several close relatives, including A. moorii, A. villwocki, A. orthodus, A. embera, A. yariguies, and A. bopiensis, and provided the formal diagnoses needed to distinguish it within that complex. As a recently described taxon with a restricted distribution in northwestern South America, it has attracted limited attention from researchers or hobbyists since its publication.
Morphology
Astyanax boliviensis is a moderately sized characid reaching a maximum recorded standard length of 3.5 in, based on male or unsexed specimens reported by FishBase. The body is laterally compressed in cross section, the typical form for active mid-water characids. Dorsal fin rays number nine soft rays.
The species' diagnostic features within the orthodus species-group are centred on the pigmentation of the flanks: a series of chevron-shaped extensions of dark pigment run along the lateral midline from the humeral region — just behind the opercle — through to the caudal peduncle, giving the lateral stripe an angular, pointed appearance rather than the smooth or diffuse pattern seen in related species. The caudal peduncle itself bears a rhomboidal (diamond-shaped) dark spot, another character used to separate it from congeners. These features, combined with the standard meristic and morphometric data gathered from the type series, form the basis of the formal diagnosis.
Habitat
Astyanax boliviensis is recorded from the upper Amazon River basin of Bolivia and Peru, with type localities in the Madidi and Mamoré river systems of Bolivia. FishBase classifies it as benthopelagic — associated with or near the bottom but also active in the water column — in freshwater tropical environments. The broader Madidi and Mamoré drainages encompass a range of Amazonian habitats, from Andean foothill rivers through lowland floodplain systems, and the species has been characterised as tropical on the basis of its geographic range.
Detailed habitat data at the population level — precise water chemistry, substrate, vegetation associations, or microhabitat preferences within those rivers — have not been published in the sources available. Given the general ecology of Astyanax species in comparable Amazonian and sub-Andean drainages, benthopelagic activity in slow to moderate current over sand, gravel, or leaf litter substrates with access to both open water and marginal cover would be ecologically consistent, but those specifics are not confirmed for this species.
Feeding
No published studies on the diet of Astyanax boliviensis in the wild are available in the current literature. The genus Astyanax is broadly omnivorous across its range, with different species and populations taking varying proportions of aquatic invertebrates, terrestrial insects, plant material, algae, and small fish depending on local availability. Members of the orthodus group, the assemblage to which boliviensis belongs, appear to occupy similar generalist niches where studied.
In an aquarium context, closely related Astyanax species accept a wide range of prepared foods including flake and small pellets, supplemented by frozen or live invertebrates such as bloodworm, Daphnia, and brine shrimp. Such a diet would be a reasonable starting assumption for boliviensis, though the species' specific nutritional requirements in captivity have not been documented.
Mating
Reproductive behaviour specific to Astyanax boliviensis has not been documented in the scientific literature available. Astyanax species in general are egg-scattering open spawners with no parental care, a reproductive strategy that is ancestral and widespread across Characidae. Males typically pursue females during spawning events, and eggs are scattered among fine-leaved vegetation, over substrate, or in open water depending on the species and context.
Given the orthodus group's ecology and distribution in flowing Amazonian systems, spawning is likely to be associated with the availability of aquatic vegetation or submerged structure that provides some physical adhesion or cover for the eggs, as is common in the genus. These are working inferences from family-level biology; breeding behaviour for this species specifically remains undescribed.
Breeding
Breeding of Astyanax boliviensis in captivity has not been reported in available hobby or scientific literature. Based on the general reproductive biology of the genus, eggs would be expected to be small, non-adhesive or weakly adhesive, and scattered among plants or over open substrate, with hatching occurring within one to three days at tropical temperatures and no parental investment beyond the spawning act itself. Fry would be very small at hatching and would require appropriately fine first foods.
FishBase rates the species' population resilience as high, with a minimum population doubling time of less than 15 months — a figure consistent with the fast generation times and large clutch sizes typical of small-to-medium Astyanax. Whether this reflects documented breeding data or modelled estimates from life-history parameters is not confirmed in the primary sources consulted.
In the aquarium
Astyanax boliviensis is not established in the aquarium hobby and is not available through the ornamental fish trade as far as current records indicate. No husbandry accounts exist in hobbyist literature or online fishkeeping communities. It is a scientifically described species known only from wild collections in Bolivia and Peru.
For comparison, other members of the orthodus group and Astyanax more broadly are peaceful to mildly nippy, schooling fish suited to community aquaria of appropriate size, with straightforward care requirements in the middle temperature and pH range typical of Amazonian tributaries. Whether boliviensis would be suitable for or available to hobbyists cannot be stated with confidence in the absence of any captive-husbandry data.
Conservation
Astyanax boliviensis has not been evaluated by the IUCN Red List and carries a status of Not Evaluated (NE) as confirmed by FishBase (Reference 130435, Version 2025-2). The species is not listed on CITES appendices. As a recently described species (2018) with a distribution confined to the upper Amazon drainages of Bolivia and Peru, it falls within a region subject to ongoing deforestation, habitat modification from agriculture and road construction, and changes in river hydrology.
The Madidi river system in Bolivia lies partly within the Madidi National Park, one of South America's most biodiverse protected areas, which provides some degree of habitat protection for species within its boundaries. Whether the populations described as the type series fall within or outside protected catchments is not detailed in the available sources. A formal IUCN assessment has not been undertaken, and the species' actual conservation status in terms of population size and trend is unknown.