Diagnosis: adipose fin always present; anterior nostrils closer to each other than posterior ones; snout reaching slightly beyond lower jaw; nasal barbel always reaching beyond orbit; eyes rather large (horizontal diameter 26,8-33,1% HL); inner side of pectoral spine feebly serrated (Ref. 43912).

Description: 8-10 branched pectoral fin rays; 38-53 branched anal fin rays; 43-47 non-fused vertebrae; 8-10 branchiostegal rays on one side of head; caudal peduncle longer than deep; nasal barbel at least reaches to posterior border of eye and at maximum to posterior border of opercle; maxillary barbel reaches at least to posterior border of opercle and at maximum to midway of pectoral spine; inner mandibular barbels short and never reach beyond center of eye; outer mandibular barbels at least reaching to posterior border of eye and at maximum to posterior opercle border; dorsal and/or pectoral spines sometimes provided with a filamentous prolongation; some specimens totally or partially lack pelvic fins (Ref. 43912). Schilbe tumbanus shows some affinities with the sympatric species S. grenfelli which also has the anterior nostrils closer to each other than the posterior ones, but S. tumbanus is easily distinguished from this species by the longer nasal barbel always reaching beyond the orbit, while never reaching beyond the posterior border of the eye in S. grenfelli (Ref. 43912).

Coloration: preserved specimens: head and back brown-black; flanks somewhat paler, sometimes more or less irregularly stained; belly ventrally whitish, laterally speckled; all fins more or less greyish speckled (Ref. 43912). In life: grey-bluish, with pale blue-green metallic reflections; back and head darker, paler ventrally; unclear, dark post-opercular spot; eye greyish golden with green reflection; fins greyish, more or less dark, especially dorsal, caudal and pectoral fins (based on Matthes 1964; Ref. 43912).