ACANTHURIDAE Acanthurus xanthopterus (photo by Suraphong Banchongmanee) Acanthurus xanthopterus Valenciennes, 1835 Yellowfin Surgeonfish D IX, 25-27; A III, 23-25; P1 16-17. Body deep, 2.0-2.3 in SL (more elongate with growth). Teeth fixed, denticulate on all of margin, with expanded incurved tips. Caudal fin deeply emarginate to lunate, the caudal concavity 4.0-7.0 in SL. Caudal peduncle with 1 folding spine. Color: color pattern can change quickly from uniform purplish gray to one with alternating, very irregular, lengthwise bands of dark yellowish gray and light blue-gray about 2 scales in width; a broad yellow band extending anteriorly to eye and an irregular one posterior to eye, extending to upper end of gill opening. Size: attaining to 56 cm, commonly to 40 cm. Distribution: widespread in Indian and Pacific Oceans. Remarks: found in rocky and coral reefs, at depths greater than 10-15 m.