This species differs from its congeners by having a unique color pattern of males: anterior third of body light brown, posterior two-thirds of body dark blue, almost black dorsal region, with rows of bright blue spots, relatively large size, with about half the diameter of the pupil. It differs from all its congeners, except S. filamentosus, by having pelvic-fin bases separated by an interspaced (vs. pelvic-fin bases in contact), tip of dorsal and anal fins in males with long filamentous rays (vs. absence of filaments, or presents only on dorsal fin in S. semiocellatus and S. inaequipinnatus, or presents only on anal fin in S. chacoensis), and presence (vs. absence) of contact organs on scales of flank in males (Ref. 93219).

Description: Males of S. brousseaui differs from S. filamentosus in color pattern (the latter has an overall reddish color pattern with white spots); having urogenital papillae developed in males and females (vs. poorly developed), and by the longer dorsal-fin base 33.8-36.2% SL (vs. 29.0-31.1%), longer head 27.5-28.8% SL (vs. 25.8-26.7%), lower head 88.6-91.4% HL (vs. 96.2-107.6% ), narrower head 55.6-54.6% SL (vs. 63.4-70.7%), greater number of dorsal-fin rays, 21-22 (vs.16-19), and fewer scales in transverse series 8-9 (vs. 11-12).

Females of S. brousseaui differs from that of S. filamentosus by having lower body, 30.6-33.3% SL (vs. 34.7-36.8%); lower caudal peduncle, 11.9-12.6% SL (vs. 13.0-15.0%); shorter anal-fin base 21.9-27.8% SL (vs. 28.8-31.4%); longer head 29.2-30.6% HL (vs. 27.3-28.7%); lower head 78.1-91.6% HL (vs. 93.4-107.2%); smaller head width, 53.0-59.6% HL (vs. 62.7-64.6%); smaller eye diameter, 29.5-32.3% SL (vs. 33.6-34.9%); fewer scales in the longitudinal series of scales, 23-24 (vs. 27-29); fewer scales in the transverse series of scales, 10 (vs. 12) (Ref. 93219).