Taxonomy & naming
Astyanax ocotal was formally described by Valdez-Moreno, Rodiles-Hernández, and Schmitter-Soto in 2017, as one of nine new species named in Schmitter-Soto's comprehensive revision of Astyanax in Central and North America (Journal of Natural History 51: 1331–1424). Prior to that revision, many small-bodied Astyanax from southern Mexico and Central America were subsumed under broad names such as A. aeneus, and A. ocotal was not recognised as a distinct entity.
The valid name as recognised by Eschmeyer's Catalog of Fishes (Catalog of Fishes, California Academy of Sciences) is Astyanax ocotal Valdez-Moreno, Rodiles-Hernández & Schmitter-Soto, 2017. The species belongs to the family Characidae and the order Characiformes. Diagnostic characters separating it from its nearest congeners — including A. angustifrons and A. finitimus — were detailed in the original revision. Some older literature referred to similar Lacandon-basin Astyanax as 'Bramocharax-like' due to a comparatively deep body and multicuspid dentition, a distinction the 2017 revision formally addressed.
Morphology
Astyanax ocotal is a fusiform-bodied characid reaching up to 4 in standard length (SL), though most individuals are smaller. Meristic data from the original description record 9 dorsal soft rays and 22–24 anal soft rays; vertebral count is 31. Head length runs approximately 29–33% of SL, a moderately large-headed proportion typical of the genus.
The species shares the general Astyanax body plan: a silver-sided, laterally compressed tetra with a forked tail, a small adipose fin, and multicuspid teeth. Some craniofacial studies examining Mesoamerican lake-dwelling Astyanax have noted that populations from still, enclosed lake habitats may develop a relatively deeper body and broader snout compared with river-dwelling congeners — a pattern consistent with trophic divergence across habitat types. The extent to which A. ocotal expresses this in its lake habitats has not been exhaustively documented in the literature available for this article.
Habitat
Astyanax ocotal is known from three localities: Laguna Ocotal (the type locality), Laguna Metzabok, and the Río Tulijá, all in the Lacandon region of northern Chiapas, Mexico. The two lakes are karstic, lowland tropical waterbodies embedded within the rainforest of the Usumacinta drainage basin. FishBase characterises the species as benthopelagic, freshwater, and tropical, consistent with the broad lake-and-river habitat it occupies.
The Lacandon jungle lakes are generally warm, with the Montes Azules Biosphere Reserve providing a degree of catchment protection for a portion of the population. The Río Tulijá component of the range is subject to anthropogenic pressure; sewage input from nearby settlements has been identified by the IUCN as a concrete threat to water quality in that system. With fewer than five known locations total, the species occupies an exceptionally small geographic footprint for the genus.
Feeding
FishBase records a trophic level of 2.9 ± 0.4 for Astyanax ocotal, placing it in the omnivore-to-insectivore range typical of small characids. At this trophic level, the diet is expected to include aquatic and terrestrial invertebrates — insect larvae, small crustaceans, and surface-fallen insects — along with algae, plant material, and incidental organic detritus.
No specific dietary studies for A. ocotal are available in the published sources reviewed for this article. The genus Astyanax broadly is an opportunistic feeder, and lake-dwelling populations often show dietary flexibility tied to the productivity and prey availability of enclosed water bodies. In the aquarium, congeners of similar size readily accept a varied diet of prepared, frozen, and live foods.
Mating
No specific courtship or mating observations for Astyanax ocotal appear in the literature reviewed for this article. Members of the genus Astyanax are generally egg-scattering, open spawners that release adhesive eggs among fine-leaved aquatic plants or over the substrate, with no parental care following spawning. Spawning is typically triggered by seasonal cues — water temperature changes or rainfall events — in wild populations.
In lake habitats such as Laguna Ocotal and Laguna Metzabok, seasonal flooding and temperature variation associated with the Chiapas wet season (roughly May through October) likely influence reproductive timing, as is the case for other lacustrine characids in the Usumacinta basin. Males of related small Astyanax species are generally somewhat slimmer than females when both are in breeding condition, but formal descriptions of sexual dimorphism in A. ocotal are not documented in the available sources.
Breeding
Specific captive breeding accounts for Astyanax ocotal are not available in the literature reviewed for this article. Based on the biology of the genus, breeding would be expected to follow the typical Astyanax pattern: egg-scattering spawns over fine-leaved vegetation or submerged roots, with adhesive eggs that receive no parental attention and are vulnerable to predation by the adults themselves.
Incubation and larval development periods have not been documented for this species. Given the species' restricted range and Near Threatened status, it has not entered the ornamental trade in meaningful numbers, and captive-propagation experience with it remains essentially nil in the published hobbyist literature. Any future conservation breeding effort would likely rely on the well-established protocols developed for aquarium-available Astyanax congeners.
In the aquarium
Astyanax ocotal is not an established aquarium fish and is not commercially available through normal ornamental channels. Its very limited natural range, Near Threatened IUCN status, and lack of trade collection mean that essentially no hobbyist experience with the species has been published.
Should the species ever be kept, the care requirements of related small Mexican and Central American Astyanax provide a reasonable baseline: a spacious, well-filtered aquarium with open swimming space, tropical temperatures in the mid-to-upper 20s Celsius, neutral to slightly alkaline water chemistry reflecting the karstic lakes of its native range, and a varied omnivorous diet. As a schooling characid it would be expected to do best in groups. In practice, aquarists interested in the Lacandon fauna are more likely to encounter congeners such as A. mexicanus, the Mexican tetra, which is widely available and well documented in captivity.
Conservation
Astyanax ocotal is assessed as Near Threatened (NT) on the IUCN Red List (assessed 5 February 2019, criterion B1a+2a). The assessment notes that the species is known from fewer than five locations — Laguna Ocotal, Laguna Metzabok, and the Río Tulijá — with an unknown but presumed small population size and no documented continuing decline. Because decline could not be confirmed at the time of assessment, the species fell just short of Vulnerable under criterion D2.
The principal identified threat is sewage pollution entering the Río Tulijá from nearby settlements, which degrades water quality in a significant portion of the known range. Approximately 21–30% of the species' estimated population falls within the Montes Azules Biosphere Reserve, which provides partial habitat protection. The highly restricted range means that any future deterioration — whether from pollution, habitat loss, or climate-driven changes to the Lacandon lake system — could rapidly push the species toward a more critical category. No targeted conservation programme for the species is documented in the sources reviewed for this article.