MONACANTHIDAE Acreichthys tomentosus, 1.4 cm SL (photo by Koichi Shibukawa) Acreichthys tomentosus (Linnaeus, 1758) Bristle-tail Filefish D II + 27-29; A 26-28; P1 11. Body relatively oblong and strongly compressed. Dorsal spine above posterior half of eye; first dorsal spine long, 1.0-1.1 in head length, with 7-9 downwardly directed barbs on posterolateral parts. Gill opening short oblique slit below posterior one-third of eye. Pelvic terminus composed of 3 segments of encasing scales and movable dorso-ventrally. Color: mottled brown to yellowish brown with an irregular longitudinal, slightly curved light yellow line on anterior side of body from gill opening to above anterior part of anal fin; caudal fin with 2-3 transverse dark brown bars. Size: maximum 12 cm. Distribution: from west coast of peninsular Malaysia eastward to Solomon Islands, north to southern Japan. Remarks: occurring in seagrass beds and sandy bottoms.