Species: Bathygobius mystacium, Island Frillfin, Island Frillfin Goby

Bathygobius mystacium Ginsburg, 1947

Island Frillfin, Island Frillfin Goby

Body robust; head broad, depressed, with pores; snout bluntly rounded; eyes large, close together; mouth moderate sized, relatively horizontal, top jaw 9.2-11 (rarely to 11.7) % of SL; tongue is notched; jaw teeth in bands, without canines; teeth in upper jaw in a narrow band, outermost teeth enlarged, without canines; gill membranes broadly joined to body under throat, with 5 rays; dorsal fin VI (none elongate) + I, 8-9; length of 2nd dorsal base > distance from 2nd dorsal base to tail fin; anal I, 7-8; pectoral 18-21, upper 4 (3-5) rays free, silky threads; pelvic fins I, 5, united to form a disc; tail fin rounded; scales large, rough, 35 (33-36) in lateral series, present on midline of nape to well before a line through rear edge of preopercle; no scales on cheek or operculum; no lateral line.

Grayish brown; upper half of body with 3 distinct dark saddles; lower body with a row of 6-7 irregular to squarish, dark, pupil-to eye-sized blotches; 1st dorsal fin with 1-3 dark spotted stripes and a yellow outer edge, sometimes uniform dark in large fish; a large dark blotch on lower 2/3 of tail fin base that joins a small blotch above it on tail base, outer part of tail fin with 3-4 narrow dark bars; yellowish scale edges form zigzag yellow lines along body.

Reaches 7 cm.

Depth range: 0-3 m.

Habitat: shallow sand/rock habitats on the seaward sides of islands.

Florida to Brazil