因为当fish当“鱼肉”讲时，是不可数名词，无复数形式。
n. 鱼；鱼肉；双鱼座；接合板；（非正式）怪人；（非正式）鱼雷
v. 钓鱼，捕鱼；搜寻；打听消息；打捞；用接合板修补
Every year at this season, fishermen go out to sea to fish.
每年到了这个季节，渔民们都会出海捕鱼。
I'll go to the market and fish for what happened to their family.
我去集市上打听一下他们家的消息。
I caught a big fish in the lake today.
我今天在湖里钓了条很大的鱼。
Fish can just live in water.
鱼只能在水里生存。
I had rice and fish for dinner.
我晚饭吃的大米和鱼肉。
This fish dish in particular was delicious.
这道鱼特别好吃。
