looking for a chance to strike. 找准机会发动进攻

217. The commotion attracts dorado,
     骚动引来了麻哈脂鲤
218. known locally as the river tiger.
     当地人称之为“河中之虎”
219. They patrol the feeding shoals,
     它们穿梭于觅食的鱼群中
220. looking for a chance to strike.
     找准机会发动进攻
221. And waiting in the wings,
     有些鱼则守在一旁等待
222. ready to pick off any injured fish,
     时刻准备攻击任何受伤的鱼
223. are the piranhas.
     它们就是锯脂鲤

来自《行星地球 第一季 第三集 Planet Earth S01E03 淡水》第 220 行