This species is distinguished from its congeners by having a vertical dark bar on the base of the caudal-fin rays (vs. none), and by the lateral line (LL1 and LL2, rarely LL3) followed by a middle trunk line composed of 1-30 tiny neuromasts, extending to flank, below the dorsal fin or, at times, to caudal peduncle near the caudal-fin base, in all specimens larger than 35.0 mm SL (vs. tiny neuromasts absent); differs further from its congeners except I. parkoi by its general body color gray, dark on the dorsal region and gradually pale ventrally, no spots nor longitudinal stripes (vs. no general gray color, with spots or longitudinal stripes); differs from I. parkoi by the fewer opercular odontodes, 10-12 (vs. 22); and by the caudal-fin margin circular with attenuated edges (vs. truncated) (Ref. 91742).