Distinguished from all congeners by its smaller distance between dark lateral stripe and ventral midline in males (distance fitting 2.6 times into body depth at pelvic-fin origin vs. 1.7-2.1 in other species) and horizontal through ventral border of dark lateral stripe extending through
ventral half of eye (vs. extending through dorsal half of eye). Can be further diagnosed from all, except Sundadanio rubellus and S. echinus, by having of a weak reticulate pattern over the dorsal and lateral body surfaces (vs. absence). Differs also by the following combination of characters: large adult body size (largest specimen examined 19.4 mm SL); live males with orangelight green sheen present across dorsal body surface, an intense red-orange secondary lateral stripe, bordering ventral edge of orange-light green sheen from point posterior to opercular opening to point opposite middle of anal fin, and an intense black-red marking across anterior portion of anal fin; preserved males with a well developed dark lateral stripe, deepest anteriorly, covering entire window in body musculature; presence of a secondary lateral stripe of small melanophores running parallel to dark lateral stripe along its ventral margin from posterior to opercular opening to point opposite middle of anal fin, often occluded by ventral edge of dark lateral stripe in mature males; absence of dusky markings on distal tips of dorsal and caudal fins; presence of enlarged scales next to window in body musculature; scales posterior to enlarged scales next to window in body musculature and
anterior to anal-fin origin with a single small tubercle at center; complete covering of scales on
caudal peduncle (Ref. 88800).
Description: Dorsal-fin rays ii.6.i; anal-fin rays iii.6; pectoral-fin rays i.6.ii; pelvic-fin rays i.5.i (Ref. 88800).