fish in troubled waters原义是在水中捉鱼，引申为浑水摸鱼；趁火打劫；陷于混乱。

【例句】
A man of good character will not fish in troubled water.
一个高尚的人是不会浑水摸鱼的。

I refused to let them come here because i knew they only wanted to fish in troubled waters.
我拒绝他们来这里，因为我知道他们只想浑水摸鱼。