Diagnosis: Body slender, depth about 20% of standard length; scutes beginning at isthmus, or just behind, very strongly keeled, 12-15 pre-pelvic and 6-8 post-pelvic scutes; lower jaw projecting, toothless; no teeth on premaxillae or maxillae; posterior supra-maxilla as deep as maxilla blade and with long slender anterior shaft; lower gill rakers 24-31; pelvic fin with 1 unbranched and 6-7 branched rays, its insertion just before dorsal fin origin; anal fin rays 20-23; scales in lateral series 35-40 (Ref. 188, 2263). It differs from Nannothrissa stewarti in having more gillrakers, 24-31 vs. 20-23, more anal fin rays, 20-23 vs. 17-19, and more scales in lateral series, 35-40 vs. 34-35 (Ref. 188, 2263, 94752).
Description: Depth of body 4 to 5 times in its length; caudal peduncle longer than deep (Ref. 2263). Snout a little shorter than diameter of eye, which is rather more than 1/3 the length of head; lower jaw a little projecting, toothless; no teeth on pre-maxillary and maxillary; maxillary extending to vertical from anterior edge of eye; posterior supra-maxilla half as long as maxilla (Ref. 188, 2263, 93833). Lower gillrakers 24-31 (Ref. 188, 93833). Dorsal fin with 12-15 rays; anal fin with 20-23 rays; pectoral fin with 11-12 rays; pelvic fin with 1 unbranched and 6-7 branched rays, its insertion about half eye diameter before dorsal fin origin; caudal fin with 18-19 rays (Ref. 188, 2263, 93833, 94751). Scales: 35-42 in a longitudinal series (Ref. 188, 2263, 93833, 94751). Scutes very strongly keeled, beginning at isthmus or just behind; 12-15 pre-pelvic and 6-8 post-pelvic scutes (Ref. 188, 2263). Number of vertebrae 39-40 (Ref. 94751).
Colouration: More or less transparent, entirely silvery with pearly blue-green and pink reflections; dorsal region slightly darker; top of head, tip of snout and chin black; eye black; ventral scutes and base of impaired fins blackish; ventral and anal fins transparent, pectoral and dorsal fins slightly darkened, lobes of caudal fin blackish; a weak black band on the caudal peduncle, widening towards the base of the latter, and clearly visible in preserved specimens (Ref. 41580).