长腰鲔(Thunnus tonggol)，又名小黄鳍鲔、黑鳍串、串仔、长实、长翼，为为鲭科金枪鱼属的其中一种。可做为食用鱼、游钓鱼。

本鱼身体呈纺锤形，体长可达0.7米。第二个背鳍比第一背鳍更高; 胸鳍是短的到中等长度; 泳鳔不存在或不发达。下侧与腹面银白色有无色的被排列成水平导向的列的细长的椭圆形的斑点，背鳍、胸鳍与腹鳍是黑色;第二个背鳍与臀鳍的顶端褪色成黄色;臀鳍是银色;背部与肛门的离鳍是黄色的有浅灰色的边缘;尾鳍是黑色。

Thunnus tonggol is a species of tuna of tropical Indo-West Pacific waters.

It is commonly known as the longtail tuna or northern bluefin tuna. The usage of the latter name, mainly in Australia to distinguish it from the southern bluefin tuna, leads to easy confusion with Thunnus thynnus of the Atlantic and Thunnus orientalis of the North Pacific. Compared to these "true" bluefins, Thunnus tonggol is more slender and has shorter pectoral fins.