fish一条鱼可数还是不可数

　　There are about 30 000 species of fish in the world.

　　世界上约有3万种鱼。

　　Fishing is good at high water.

　　高水位有利于钓鱼。

　　How can you tell what sex a fish is?

　　你怎样辨别一条鱼的雌雄？

　　I don't like fish.

　　我不喜欢鱼。

　　You need a licence to fish in this river.

　　你在这条河里钓鱼要有许可证。