Sundadanio echinus Conway, Kottelat & Tan 2011

Distinguished from all congeners by its snout length, 15-19% HL and body depth at pelvic-fin origin, 25-30 % SL. Differs from all other species, except Sundadnio rubellus, by the presence of the secondary lateral stripe in both sexes. Can be further diagnosed by following combination of characters: large adult body size (largest specimen examined 17.8 mm SL); live males with emerald green sheen present across dorsal body surface, an intense red secondary lateral stripe, running along ventral edge of emerald green sheen from posterior to opercular opening to point opposite middle of anal fin, and an intense black marking across anterior portion of anal fin; preserved males with a well developed dark lateral stripe of roughly uniform depth along entire length, horizontal through ventral border of which, when brought forward, extending through dorsal half of eye; presence of a distinctive 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; presence of reticulate pattern along dorsal body surface posterior to dorsal-fin origin; absence of dusky markings on dorsal and caudal fins; presence of enlarged scales next to window in body musculature; complete covering of scales on caudal peduncle; scales posterior to enlarged scales next to window in body musculature and anterior to anal-fin origin with a single small tubercle at center (Ref. 88800).Description: Dorsal-fin rays ii.6.i; anal- fin rays iii.6; pectoral-fin rays i.6-7.i-ii; pelvic-fin rays i.5.i (Ref. 88800).

Dorsal soft rays (total): 9; Analsoft rays: 9; Vertebrae: 34 - 35

Inhabits peat swamp forests (Ref. 88800).

Sundadanio echinus is a danionin in the family Cyprinidae. It is endemic to Borneo and found in West Kalimantan (Indonesia) and western Sarawak (Malaysia). It lives in peat swamps and blackwater streams.

Sundadanio echinus reaches a maximum size of 2.1 cm (0.83 in) standard length.