黑尾刺尾鱼 Acanthurus nigricauda hēi wěi cì wěi yú

黑尾刺尾鱼，Acanthurus nigricauda,体呈椭圆形而侧扁。头小，头背部轮廓随着成长而凸出。口小，端位，上下颌各具一列扁平齿，齿固定不可动，齿缘具缺刻。背鳍及臀鳍硬棘尖锐，分别具XI棘及III棘，各鳍条皆不延长；胸鳍近三角形；尾鳍弯月形，随着成长，上下叶逐渐延长。体一致为紫灰至黑褐色，体侧无任何小班点及线纹，但在鳃盖上方，眼正后方具「一」字形黑斑，而在尾柄棘向前亦具一黑斑。背鳍及臀鳍黑褐色，背鳍基底具一有时不显之紫色纹，鳍缘为淡蓝色；尾鳍褐色，鳍缘为白色，基部具白色弧带；胸鳍基部黑色，余淡白色；腹鳍黑色，鳍缘为淡蓝色；尾柄棘沟缘为黑褐色。

百度翻译提供：

Acanthurus nigricauda has an oval body and flat sides. The head is small, and the back contour of the head protrudes as it grows. The mouth is small, the end position, the upper and lower jaw have a row of flat teeth, the teeth are fixed and immovable, and the tooth margin has notches. Dorsal fin and gluteal fin hard spines are sharp, with Xi spines and III spines respectively, and each fin ray is not extended; Pectoral fins nearly triangular; The caudal fin is crescent shaped, and the upper and lower leaves gradually extend with growth. The body is consistent from purple gray to black brown, without any small shift points and lines on the side of the body, but there is a "I" shaped black spot directly behind the eye above the operculum, and there is also a black spot forward of the caudal stalk spine. Dorsal fin and gluteal fin are dark brown, the base of dorsal fin has a sometimes invisible purple stripe, and the fin edge is light blue; The tail fin is brown, the fin edge is white, and the base has a white arc band; The base of pectoral fin is black, and the rest is light white; The ventral fin is black and the fin edge is light blue; The margin of spinous groove of caudal stalk is black brown.