Cocos goby, Cocos frill-goby, Cocos frillgoby, Dusky sand-goby, Common goby, Tidepool goby, Coco-karteldikkop, Sujikumohaze, スジクモハゼ, 椰子深鰕虎魚, 椰子黑鰕虎,

Synonymes
Bathygobius fuscus pulcher (Fowler, 1945)
Bathygobius versicolor (Fowler, 1945)
Chlamydes versicolor (Fowler, 1945)
Gobius cocosensis (Bleeker, 1854)
Gobius elmeri (Herre, 1940)
Gobius sandvicensis (Günther, 1880)
Gobius ophthalmicus (Weber, 1909)
Rhinogobius corallinus (Jordan & Seale, 1906)
Rhinogobius ophthalmicus (Weber, 1909)

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Description
Dorsal spines (total): 7; Dorsal soft rays (total): 8-10 (usually: 9); Anal spine: 1; Anal soft rays: 7-8 (usually: 8); Pectoral fin rays: 16-20 (usually: 18); Pelvic fin rays: I, 5; Caudal soft rays: 17 (Segmented); Longitudinal scale series: 33-39 (usually: 35); Transverse scales: 18; Predorsal scales: 6-14, nearly reaching to above rear margin of preopercle; Depth of body: 5.0 in SL. Body moderately elongate and compressed. Head subcylindrical; Gill opening not extending anteriorly to a vertical through posterior margin of preopercle; Mental flap well developed, slightly protruding posterolaterally; No flap-like projection at tip of anterior nostril; Anterior margin of tongue notched. Upper 4-5 pectoral rays branched to base, tips membrane-free; Pelvic fins united medially; Frenum present, with no distinct projection at middle of posterior margin. Scales ctenoid posteriorly, cycloid anteriorly; Scales absent on cheek and operculum. Sensory canals and pores present on head; Longitudinal pattern of sensory papillae on cheek; Uniserial transverse row of sensory papillae just behind chin. Rounded caudal fin; Ctenoid body scales, becoming cycloid on abdomen, breast and nape; Depressed head, width greater than depth. Mouth oblique and terminally placed with upper jaw protruding little over the lower one. Lips are fleshy. Eyes placed dorso-laterally on the head with convex upper margin. Inter orbital area is one third of eye diameter and flat. Snout is wide and gradually depressing. Small pointed teeth in both jaws. Gill opening is restricted just below the nape region. Max. length: 12.0 cm TL. Depth range: 0 - 10 m, usually: 0 - 2 m.

Color
Body is mottled brown and which distinguishes this species. There are five whitish brown saddle like patches appear all over the body. Lower half body sides are with seven rectangular brown blotches. Ventral profile is mostly transparent. Small white and brown blotches appear on the cheek, some appearing as group of pigmented spots. Caudal and second dorsal fin rays are with alternating white and brown blotches. Caudal and pectoral fin membrane is transparent. Dorsal fin membrane is with a white pigmented patch in the middle portion. Horizontal black line near base of fist dorsal. Most of the scale lining is transparent. Eye socket margins are with alternating brown blotches. Lips are pigmented with mottled brown in altering positions. Operculum margin with light greenish pigmentation. Anal fin is transparent.

Etymology
Bathygobius: from Greek, bathys = deep + from Latin, gobius = gudgeon.
cocosensis: from the Territory of the Cocos (Keeling) Islands, also called Cocos Islands and Keeling Islands. It' a territory of Australia, located in the Indian Ocean, southwest of Christmas Island and approximately midway between Australia and Sri Lanka. The territory consists of two atolls and 27 coral islands, of which two, West Island and Home Island, are inhabited with a total population of approximately 600.
Original description: Gobius cocosensis Bleeker, 1854 - Type locality: Cocos-Keeling Islands, Indian Ocean.

Distribution
Indo-West Pacific: Eastern Cape and KwaZulu-Natal (South Africa), East Africa, Persian Gulf, Seychelles, Madagascar and Mascarenes (La Réunion, Mauritius, Rodrigues), east to Hawaiian Islands (U.S.A.) and Pitcairn, north to southern Japan, south to Western Australia, Queensland (Australia), New Caledonia and Rapa (French Polynesia).