Astyanax aramburui is a species of freshwater ray-finned fish belonging to the family Acestrorhamphidae, the American characins. This fish is found in the rivers of South America, although it is restricted to a relatively small region within the Paraná and Uruguay river basins of Argentina. It was named after the scientist who established a professional presence for ichthyology in the country, Raúl Arámburu. Considered a near-threatened species by the IUCN, its range includes creeks in a sub-basin affected by various forms of pollution.

Its taxonomy faces some mild debate, but this is not unusual regarding Astyanax as a genus; further, it can be differentiated from various similar congeners by way of several distinctive features. The most notable of these is the presence of small protrusions on the head and scales of sexually mature male specimens, which only have a limited presence in other members of the genus Astyanax. Otherwise, its scales are silver with a touch of yellow, and it has a single black humeral spot. Little has been published about its physiology or feeding habits.

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