Mystus catapogon is distinguished from other species of Mystus by having the following characters: yellowish body without any stripes; black triangular mark outside operculum; long and shallow cephalic groove divided into two peripheral fontanelles; occipital process short, not reaching base of dorsal fin; shorter snout; maxillary barbels very long, reaching behind caudal fin base; nasal barbels reaching a little behind occiput and almost as long as head; and longer outer mandibular barbels reaching nearly base of pelvic-fin origin and inner mandibular barbels extending to the middle of pectoral fin. It further differs from its congeners by having elongated rays on dorsal fin which is higher than the body (Ref. 108436).