Diagnosis: Congoglanis inga differs from C. sagitta in having a longer maxillary barbel, reaching well past vertical through anterior margin of orbit vs. not reaching to orbit; a deeper caudal peduncle, 7-8% of standard length vs. 6%; and less slender caudal peduncle, its depth 2.1-2.9 times in its length vs. 3.1-4.0; a longer pelvic fin, 22-25% of standard length vs. 19-21%; a more posteriorly placed anal fin, anal-fin origin approximately at tip of adpressed pelvic fin vs. origin well in advance of tip of adpressed pelvic fin; longer anal-fin rays, posterior rays of adpressed anal fin extend well past vertical through posterior limit of adipose fin vs. posterior rays extend to vertical through posterior limit of adipose fin; and fewer vertebrae, 35-37 vs. 39-41 (Ref. 88958). It differs from C. alula in having a longer maxillary barbel, reaching well past vertical through anterior margin of orbit vs. not reaching the orbit; a shorter pelvic fin, 19-21% of standard length vs. 24-28%; a longer postorbital length, 32-35% of head length vs. 27-31%; a relatively wide interorbital width, 2 times eye-diameter vs. 1.5 times; and longer anal-fin rays, posterior rays of adpressed anal fin extend well past vertical through posterior limit of adipose fin vs. posterior rays extend to vertical through posterior limit of adipose fin (Ref. 88958).

Description: A relatively robust species, with body somewhat elongate, nearly cylindrical from head to anal-fin origin, with abdominal region slightly flattened, progressively tapering further posteriorly; greatest body depth and width located at dorsal-fin origin; body smooth skinned and firm (Ref. 88958). Dorsal and ventral profiles of body from head to vertical through anal fin nearly horizontal but converge from vertical through anal-fin origin to posterior end of caudal peduncle (Ref. 88958). Lateral line complete, running along midlateral surface of body (Ref. 88958). Caudal peduncle relatively short, thick, and compressed, but nearly as wide as high at terminus of anal-fin base; least depth of caudal peduncle approximately located at middle of its length (Ref. 88958). Mouth subterminal, small, ovoid when open, with fleshy tuberculate upper lip and smooth firm lower lip, flanked to each side by tuberculate section (Ref. 88958). Barbels tuberculate and distally tapered; maxillary barbel longest, reaching well past vertical through anterior margin of eye and extending to, or nearly to, margin of branchiostegal membrane; inner mandibular shortest, with base situated slightly lateral of midline and approximately in line with lateral margin of smooth portion of lower lip; outer mandibular barbel arises from angle of mouth and extends posteriorly approximately one-half distance to branchiostegal membrane (Ref. 88958). Dorsal fin falcate, first branched ray longest, with i,6, i,6,i or i,7 rays; adipose-fin origin located at vertical through anal-fin origin; Pectoral fin large and falcate, with i,11 or i,12 rays; pelvic fin with i,5 rays; anal fin small, with distal margin straight, with iv,6 or iv,7 rays; caudal fin deeply forked, asymmetrical, with ventral lobe longer and broader than dorsal lobe (Ref. 88958).

Colouration: Bodu coloration generally dark, with variably distinct lighter regions on overall dark brown body; in lightly pigmented specimens, body darker dorsally with brown coloration extending ventral of lateral line on abdomen and caudal peduncle; boundary between dark brown pigmentation of dorsal and dorsolateral regions and lighter coloration of ventrolateral and ventral regions relatively straight and horizontal from pectoral-fin base to caudal peduncle (Ref. 88958). Lightly pigmented specimens with six pale patches distributed in irregular horizontal line along dorsolateral part of body (Ref. 88958).