Easily identified by the dark black bar extending downward through the eye and the yellow-brown body color; during courtship, both males and females with 9-11 black bars on their flanks and a red border on the edge of the dorsal fins; black eye bar becomes prominent; males develop a dusky flush to their throats and lower jaw (Ref. 44091).

Largest Insularigobius recorded; possesses a relatively high scale count in horizontal series, 47-52, usually 48-50; high predorsal scale count, always fully scaled, 16-23, usually 19-20; belly anteriorly almost always scaled close to pelvic base; breast always with many embedded scales; up to five rows of teeth in upper jaw and up to six in lower jaw (Ref. 34009).