Diagnosis: head depressed (Ref. 43434), broad, about 1.3-1.6 times as long as wide (Ref. 28714, 30488, 57125), squarish when viewed from above (Ref. 28714), without rough texture (Ref. 3034). Head width measured at base of preopercle 58.9-71.8% head length; 12-16 gill rakers on first gill arch (Ref. 81641). Body slightly elongated, 5-6 times longer than deep (Ref. 7324, 57125, 81641). Four pairs of barbels (Ref. 34290). Premaxillary tooth plate 5-7 times longer than wide, a little shorter than and about as broad as the band of vomerine teeth (Ref. 2988). Premaxillary toothplate width less than 2.5 times in head length (Ref. 57125). Occipital process 3-5 times longer than wide (Ref. 57125, 81641). Predorsal length 2.4-2.7 times in standard length; 9-10 branched dorsal fin rays, not or only slightly filamentous (Ref. 57125, 81641). Long adipose dorsal fin present (Ref. 34290). Standard length/caudal peduncle length 2.4-2.7 (Ref. 57125). Upper lobe of caudal fin often with a short filament (Ref. 7324, 57125, 81641).

Description: head without rough texture (Ref. 3034). Snout broadly rounded, projecting beyond the lower jaw (Ref. 2988). Eye with a free border (Ref. 51936, Ref. 36901). Four pairs of circum-oral barbels, showing great variation in length, being relatively longer in smaller individuals (Ref. 34290). Maxillary barbel 1.2-3.25 times head length (Ref. 3032, Ref. 43434), reaching ventral or not quite so far in adult and reaching anal fin or caudal peduncle in juveniles (Ref. 2899). Nasal barbel 0.2-0.4 times head length (Ref. 367). External mandibular barbel 0.5-1 times head length (Ref. 3032). Internal mandibular barbel 0.36-0.64 times head length; occipital processus not reaching the interneural (Ref. 51936). Dorsal fin short with a well-developed spine (Ref. 34290). First branched fin rays of dorsal fin hardly or not filamentous (Ref. 30488, 81641), longest ray 1/3-1/4 of SL (Ref. 57125, 81641). Last ray of dorsal fin in front of inner ray of ventral fin (Ref. 4912). Dorsal spine smooth (Ref. 36900). Adipose dorsal fin 4-5x as long as deep (Ref. 43434), 1.66-2x as long as rayed dorsal (Ref. 2899). Anal fin short (Ref. 34290), 0.5-0.7x head length (Ref. 367), inserted under the last branched dorsal fin ray or just behind this (Ref. 2756). Some caudal fin rays may have filamentous extension (Ref. 34290). Upper caudal lobe comprised 3-4 times in SL (Ref. 81641). Caudal skeleton morphology described in Ref. 51975. Pectoral spine serrated along the inner side (Ref. 3032). No pectoral filaments (Ref. 367, 3036).

Coloration: dark grey-black above, creamy-white below (Ref. 34290). Body sometimes shot with gold and green (Ref. 4904). Some blackish may be present on the dorsal (Ref. 11235), anal and ventral fins (Ref. 2899). Blackish dots sometimes present on the posterior part of the back and on the adipose fin (Ref. 11235). Freshly caught fish have a greenish iridescence which soon fades to a dark greyish blue (Ref. 3023). Some juveniles may be completely blackish (Ref. 7324, 57125) with the exception of the ventral surface of the body(Ref. 81641). Some other specimens with dark brown spots on flanks and on adipose and caudal fin (Ref. 81641).