When I ask my friend if she likes my new dress, I was fishing for a compliment.
我问她是否喜欢我的新衣服时，其实是想让她夸我几句。
fish for：摸索；寻找

It's like shooting fish in a barrel.
这太简单了。

My neighbour is a cold fish.
我的邻居是一个冷漠的人。

I used to drink like a fish and get drunk all the time.
我以前酒喝得很猛而且每次都喝醉。
drink like a fish：大喝；豪饮；一大口一大口地喝酒

Why does he always enjoy being a big fish in a small pond? He deserves a better position!
为什么他总喜欢把自己大材小用呢？他可以做一个更好的职位。
A big fish in a small pond：大材小用

Now it's time to fish or cut bait. I need your answer by six o'clock tonight -- otherwise we'll leave you out of it!
现在你必须做出抉择了。我必须在今晚六点前得到你的答复，否则我们就把你排除在外。
fish or cut bait:做出决定