Differs from I. paradoxus and I. crocodilus by the following characters: ridges of head bones strongly serrated, especially in larger males (versus weakly serrated in I. crocodilus, weakly or not serrated in I. paradoxus, depending on the bones; and color pattern (dark brown ventral side, especially on head, with dark brown opercle and throat with numerous brown spots (versus light brown ventral side, throat white, rarely with a few spots in I. paradoxus and I. crocodilus). Further differs from I. paradoxus in having conspicuous dark brown to black bars in dorsal and anal fins of mature males (versus absence, or with narrow light brown bars in sexually active males) (Ref. 38647).