GOBIIDAE Acentrogobius cyanomos, 7.0 cm SL (photo by Koichi Shibukawa) Acentrogobius cyanomos (Bleeker, 1849) Blue-spotted Goby D VI+I, 10; A I, 9; P1 18; LR 28; PDS 4-7. Body moderately elongate and compressed. Head subcylindrical; jaws subequal; gill opening not extending anteriorly to a vertical through posterior margin of preopercle. Middle some spines of first dorsal fin elongate and filamentous at least in male; pelvic fins united medially; frenum present. Scales ctenoid, excluding those on nape, pectoral base and breast cycloid; cheek and operculum naked. Sensory canals and pores present on head; longitudinal pattern of sensory-papillae rows on cheek; uniserial transverse row of sensory papillae just behind chin. Color: distinct black triangular spot just above dorsal end of gill opening; 5-6 midlateral dusky spots on body; numerous bright pale-blue spots on body and dorsal and caudal fins. Size: 11.5 cm. Distribution: Indo-West Pacific. Remarks: found in tidal estuaries with sandy-mud bottom.