It is plentiful in almost the entire continent, with a habitat including the La Plata, upper Amazon, and Meta River basins.
The body shape is subrhomboidal (somewhat rhomboidal) and laterally compressed, and the scales are largely silver, with a blue or green tint on the dorsal side.
Why the genus has this name was not made clear in the original text, but could possibly refer to the large, armor-like scales of species A.
[18] The relevant habitat stretches through multiple countries, including Brazil, Argentina, Bolivia, Uruguay, and Paraguay.
[5] In environments of strong hypoxia, A. abramis can develop reversible dermal extensions, possibly as a way to increase the efficacy of aquatic surface respiration (ASR).
Previous research on similar traits had revealed a demonstrable link between morphological plasticity and ASR, and this is likely to remain the case in A.
[14] It is also known to live in sympatry with other congeners, including A. puka, A. asuncionensis, A. eigenmanniorum, and A. lineatus, specifically in the Juramento River.
The parasitic nematode worm Procamallanus (Spirocamallanus) hilarii has been recorded from a wide variety of neotropical fish species, including A.
[22] Astyanax abramis has a split spawning season, with higher reproduction activity in April and October.
The intestines can become larger in periods of food scarcity, which allows it to eat items that are more difficult for it to digest, like plant material.
[8] Other studies report that the juveniles are more herbivorous than the adults, but this is likely explained by environmental differences;[22] there is also evidence that general food abundance influences diet (such as increased allochthonous plant consumption in areas with plentiful riparian vegetation), which means that the role of A. abramis in the trophic system changes depending on the region.
[24] Astyanax abramis has been evaluated by the IUCN Red List as "Least Concern"[1] due to its wide distribution and the fact that it can easily be collected in various locations.