i>Paracanthocobitis nigrolineata can be diagnosed from other congeners by combination of the following characters: incomplete lateral line ending near insertion of dorsal fin; dorsal fin with 9½-10½ branched rays; presence of axillary pelvic lobe; side of body with black stripe ending near caudal fin, usually overlying black lateral blotches extending ventrally from lateral stripe; presence of circular black spot on upper margin of caudal-fin base; black pigment extending from lateral stripe onto pectoral-fin base; absence of marmorated pattern anterior to dorsal-fin origin; black dorsal saddles short, not connecting to lateral blotches; and upper caudal fin with 8 branched (Ref. 117351).