GOBIIDAE Bathygobius fuscus, 3.0 cm SL (photo by Ukkrit Satapoomin) Bathygobius fuscus (Rüppell, 1830) Dusky Frill Goby D VI + I, 8-10; A I, 7-8; P1 16-20; LR 31-40; PDS 10-19. Body moderately elongate and compressed. Head subcylyndrical; gill opening not extending anteriorly to a vertical through posterior margin of preopercle; mental flap well developed, trapezoid, but not protruding posterolaterally; no flap-like projection at tip of anterior nostril; anterior margin of tongue notched. Upper part of pectoral fin with filamentous free rays; pelvic fins united medially; frenum present, with no distinct projection at middle of posterior margin. Scales ctenoid posteriorly, cycloid anteriorly; head naked. Sensory canals and pores present on head; longitudinal pattern of sensory papillae on cheek; uniserial transverse row of sensory papillae just behind chin. Color: head and body gray blown dorsally, pale gray or white ventrally; a series of black blotches, each extending ventrally to ventral half of body, on midlateral body; dorsal fin with a broad yellow or orange distal margin. Size: 8.0 cm SL. Distribution: Indo-Pacific. Remarks: found in tidal estuaries, rocky or coral reefs.