Diagnosis: small species with long head, 18.8-25.0% SL; snout relatively long, 28.6-37.0% SL, with narrow cleft and peculiar structure of the inferior positioned mouth; opercular disc of males shallow, with rounded outer edge; pectoral fin long, 14.9-17.7% SL; preanal length relatively short, 65.0-71.9% SL; 79-87 lateral line scales, which tends to increase with increasing length of the fish; distinct blackish streak from tip of snout to caudal fin, which may be coverd by dark bluish spots; dorsal fin origin clearly behind pelvic fin origin (Ref. 26644).
Description: body slender, depth 4.7-6.8 times in standard length (SL); head long, 4.0-5.3 times in SL, longer than body depth; eye small, 2.8-3.7 times in head length (HL) and 14.0-1.4 times in snout length; snout length increases with age; interorbital distance 1.9-2.8 times in HL; dorsal fin origin well behind origin of pelvic fins and behind the middle of the distance between snout tip and caudal base; caudal fin relatively large, deeply forked, both lobes of equal size and pointed, usually not folded even when the fish rests on the ground; caudal peduncle 1.4-1.9 times longer than deep; pectorals as long as or a little longer than pelvics, shorter than head; postopercular organ poorly developed and oblique laminae weak, opercular organ consists of a shallow circular crater with a flat bottom; mouth cleft narrow, with 2 small lappets at each edge (Ref. 26644). Mouth inferior in adults (Ref. 26644), but terminal in juveniles (Ref. 44637). Maxillary with a rough surface (Ref. 26644).
Coloration: in life: generally plain brown with a characteristic dark brownish to blackish streak running straight from snout tip to end of caudal peduncle, width of streak equal of pupil to eye diameter, indistinct between eye and end of postopercular organ and most prominent on caudal peduncle; above this streak the color is uniformly olive and only slightly darker on back; males tend to show a weak streak above the blackish midline which is faintly lighter thus makes the upper egde of the dark streak more prominent; in females, dark midlateral streak composed of elongate spots which are merging together; small specimens do not show spots but a streak on abdomen; between pectoral and pelvic fins, area between dark streak and lateral line golden, especially in males; flanks below lateral line greyish, to whitish on belly; no dark markings below dark midlateral streak; all fins pale olive to hyaline without markings; indistinct dark brown spots at base of pectoral and pelvic fins (Ref. 26644). Alcohol preserved: general color more brownish, streak along midline more prominent, especially in females; difference between dorsal part of flanks above dark midline and below much more marked for dorsal part of body is somewhat darker than in life, the ventral part somewhat lighter; no dark pattern besides midlateral streak in preserved specimens (Ref. 26644).