Blackfin Triplefin

Male red with darker red, double red bars , black "mask" covering front and lower two-thirds of head, chest, and pectoral-fin base, narrow white bar at caudal-fin base, and basal two-thirds to three-fourths of caudal-fin black. Female translucent greenish grey with indistinct reddish blotches along back, middle of sides, and just above anal-fin base. Head, chest, and pectoral-fin base scaleless; short orbital tentacle present; mandibular pores 3-4 + 1 + 3-4. Maximum size to 3.5 cm TL (Ref. 90102).

Dorsal spines (total): 14 - 17; Dorsal soft rays (total): 7 - 10; Analspines: 1; Analsoft rays: 16 - 19

Adults are found on seaward and lagoon reefs, usually less than 5 m (Ref. 90102). Eggs are hemispherical and covered with numerous sticky threads that anchor them in the algae on the nesting sites (Ref. 240). Larvae are planktonic which occur primarily in shallow, nearshore waters (Ref. 94114). Minimum depth from Ref. 58018.

分布於西太平洋區，北從沖繩及台灣，經菲律賓，向東南至萬那杜及其他大洋洲其他島嶼，包括：社會群島、萊恩群島、薩摩亞及東加。臺灣分布於南部海域。

小型魚類，僅具學術研究價值。

體形小，圓柱狀。上頜向後延伸至瞳孔前緣下方；雄魚吻部長於雌魚；齒小，上下頜具椎形齒；鋤骨及腭骨前端具齒群。眼眶上緣觸角短，呈葉狀。鼻瓣膜為葉狀。後顳骨枝稍彎曲，呈”I”形。頤部感覺孔 3-4 +1 + 3-4。頭部、胸部及胸鰭基部無鱗。體櫛鱗，尾柄圓鱗。側線不連續，分為前後二段，前段側線為孔鱗15-20個，孔鱗側線從胸鰭基後方即稍下降，末端位於第二背鰭末端下方；後段側線具2列缺刻鱗15-20個，末端止於尾柄。側線上鱗列 4 + 1 + 4。D. III+XI-XIV+7-10； A. I+16-19； P. ii-iii + 6-7 + vi-viii (15-17)；L.l. 18 + 16-18；Vert.11-12 + 22-24。背鰭低矮，分成三枚，但長度不超過第二背鰭第一軟條；臀鰭起始於第十至第十二側線孔鱗；胸鰭末端達第六至第九臀鰭軟條。雄魚體紅色，體側帶散布深紅色條紋，頭部下方2/3處至胸部及胸鰭基部黑色，尾柄具1白色細長橫紋，尾鰭2/3-3/4部分黑色；雌魚灰綠色，體側沿體背、中央及腹側各具1列紅色斑塊。(李承運、林沛立2012/11編寫)

主要棲息於潟湖珊瑚礁至外礁的礁頂平台，水深不超過5m。以藻類為食。

Enneapterygius nigricauda, known commonly as the blacktail triplefin or the Pacific blacktail triplefin, is a species of triplefin blenny in the genus Enneapterygius. It was described by Ronald Fricke in 1997. It is found in the western Pacific Ocean from the Bonin Islands to Wake Island.