Opsariichthys kaopingensis Chen & Wu 2009

Diagnosed from all other species of the genus by the following combination of characters: absence of maxillary barbels; absence of notch on anterior tip of upper lip w; 44-48 (always45-47) scales on lateral line; predorsal scales less than 20 (always 18-19; modally 19); maxillary extending to or slightly beyond the vertical of anterior margin of orbit; a series of 4-5 (modally 5) rounded tubercles under lower jaw in adult male; and opercle and ventral side of head shiny yellow in adult male in life (Ref. 81910).Description: Dorsal fin rays iii, 7-8 (modally 7); anal fin rays iii, 8-9 (modally 9); pectoral fin rays i, 13-15 (modally 14); and pelvic fin rays i, 8-9 (modally 8) (Ref. 81910).

Dorsal soft rays (total): 10 - 11; Analsoft rays: 11 - 12; Vertebrae: 38 - 40

台灣的特有種。分布於台灣南部的高屏地區，從高屏溪到恆春半島之主要溪流中、下游及支流水域中，皆有其分布。

為台灣南部河川最主要的溪釣種類之一。食用魚，油炸或紅燒皆宜。

背鰭3(不分枝軟條)+ 7(分枝軟條)；臀鰭3(不分枝軟條)+ 9(分枝軟條)；胸鰭1(不分枝軟條)+ 14-15(分枝軟條)；腹鰭1(不分枝軟條)+ 8(分枝軟條)；側線鱗45-48；背前鱗22-23。體延長而側扁，無肉稜。頭較大，吻端圓鈍。眼較大。口裂中大，可延伸達眼前緣下方。上頜前端有微凹。體被有中型圓鱗。臀鰭在雄魚明顯延長。體背側呈灰黑色，體側銀白色。雄魚背鰭、臀鰭具黑色條紋，頭腹部呈亮黃色至淺橘黃色，胸鰭、腹鰭呈淺黃色。與粗首馬口鱲(/Opsariichthys pachycephalus/)極為相似，兩者之間的的差異，可由背前鱗22-23(vs. 25-27)以及側線鱗數45-48(vs. 51-55)加以區別。

初級淡水魚。喜好棲息在溪流中、上游及支流的潭區水域。雜食性。幼魚以藻類、有機碎屑、小型無脊椎動物為食；成魚主要攝食水生昆蟲、小型魚蝦及其他有機碎屑等。

Opsariichthys kaopingensis is a species of cyprinid fish. It is endemic to southern Taiwan and has a maximum standard length of 11.4 centimetres (4.5 in). The specific name kaopingensis refers to its type locality, Kaoping River.