Do you know fish come out of eggs when they are born(出生)? Before little fish comes out of the egg, it eats the food in the egg. When it is big, it leaves(离开) the egg. It swims in the water. You can see the eyes and nose. Its ears are hidden(藏) in the head. Some fish eat other fish. Some fish have small mouths and teeth(牙齿) and they often eat plants(植物).