Description
Dorsal spines (total): 7; Dorsal soft rays (total): 10; Anal spines: 1; Anal soft rays: 8-9 (usually: 9); Pectoral fin rays: 16-17 (usually: 17); Pelvic fin rays: I, 5; Segmented caudal fin rays: 9 + 8, including: 6-7 + 6-7 branched rays; Dorsal unsegmented caudal fin rays: 6-8 (usually: 7); Ventral unsegmented caudal fin rays: 5-7 (usually: 6); Depth of body: 4.8-5.4 in SL; Longitudinal scales: 23-25 (usually: 23); Transverse scales from anal fin origin upward and forward to base of first dorsal fin 9-12 (usually: 11); Transverse scales from anal-fin origin upward and backward to base of second dorsal fin: 8-10 (usually: 9); Transverse scales from second dorsal fin origin downward and backward to base of anal fin: 7-9 (usually: 9); Prepelvic scales 3-5 (usually: 4); Circumpeduncular scales: 12; Gill rakers 3-4 + 9; Pseudobranchial filaments: 6-7. Cheek spine moderately long: 21.3–26.7% in head length, but not reaching posteriorly to posterior margin of opercular membrane; Fourth spine of first dorsal fin greatly elongate, filamentous, longer than preceding spine; Base of pectoral fin broadly covered by embedded cycloid scales; Rounded caudal fin. Max. length: 7.5 cm SL. Depth range: 0 - 3 m.

Color
Ground color of head and body light gray or light bluish gray dorsally, pale beige or yellowish white ventrally; Two short, parallel horizontal dark gray or grayish brown stripes from posteroventral margin of eye to a vertical line through posterior margin of preopecle, upper one of which continuous with a horizontal dusky line along upper margin of operculum; A series of dusky vague blotches (tinged with red or brown) from posterior corner of jaws to posterior margin of operclum; Several minute pale blue spots scattered on cheek and operculum; Ground color of eye light gray or dark gray; Four or Five short transverse lines on dorsal surface of eye; Pupil encircled by pale yellow or reddish yellow; A conspicuous blackish, ovoid spot (slightly smaller than eye), tinged with blue, just above pectoral-fin base; A series of five horizontally elongate dusky blotches on mid-lateral body, and pair of similar colored blotches on side of belly; Occipital region and nape with numerous close-set, small irregular shaped, dark reddish gray spots; Five or six horizontal series of minute brownish gray dots on side of body; Numerous minute pale blue dots scattered on body (those on belly conspicuous and enlarged); Ground color of fins nearly transparent; Dorsal and caudal fins with reddish lines and/or dots.

Etymology
Gladiogobius: from Latin gladius = Roman short sword, "gladius” + from Latin, gobius = gudgeon. Referring to large spine, “shaped like a rooster’s spur,” at posterior angle of preopercle of Gladiogobius ensifer.
ensifer: from Latin, ensis = sword + from Latin, fero ‎= bear. One who bears or carries a sword. Referring to large spine, “shaped like a rooster’s spur,” at posterior angle of preopercle.
Original description: Gladiogobius ensifer Herre, 1933 - Type locality: near entrance to Majalibit Inlet, Waigio Island (Pulau Waigeo, Papua Barat, Indonesia, western Pacific).

Distribution
Indo-West Pacific: Seychelles east to Philippines, New Ireland (Papua New Guinea), Solomon Islands and New Caledonia, north to southern Japan.

Biology
Inhabits tide pools of sandy intertidal areas of lagoons, bays, and river mouths. Also lives in sheltered sandy bays and estuaries among rubble and in lagoons along edges of coral patches. Usually found in small loose groups.