Diagnosed from most members of the genus Astyanax and include it in the A. bimaculatus species group by its horizontally elongate oval, black humeral spot, lozenge shaped caudal-peduncle spot continued into middle caudal-fin rays, and two brown bars in the humeral region. Can be differentiated from species of this group by the following combination of characters: a reticulate scale pattern, a black longitudinal stripe, a toothless maxilla, larger dentary teeth, teeth of the inner row of the premaxilla with five to seven cusps, body depth 33.3-39.9% of SL, predorsal distance 51.7-55.5% of SL, caudal peduncle depth 12.0-13.4% of SL, head length 23.9-26.4% of SL, orbital diameter 28.5- 34.3% of HL, interorbital width 32.7-38.4% of HL, 36-38 perforated scales along the lateral line, and 22-26 branched anal-fin rays, 25-29 total (Ref. 75035).

Description: Dorsal fin ii,9; Anal fin iii-iv,22-25; Pectoral fin i11-14; Pelvic fin i7 (Ref. 75035).