Do Fish Never Sleep?

When you think of sleep, you think of eyelids closing over your eyes. But most fish do not close their eyes, yet they do sleep. 

Most fish sleep by keeping very still in the water. In this way ,their bodies rest, just as your body does while you are asleep. But when a fish sleeps, it is not the same deep, sound sleep that you are accustomed to, and a slight shake in the water will disturb it.

Translation for Reference(参考译文)

鱼从不睡觉吗？

当你想到睡觉的时候，你就会想到闭眼皮。但是大部分鱼儿睡觉却并不闭上眼睛。

绝大部分的鱼在水中是以保持一动不动的状态来睡觉的。它们就是以这种方式使自己的身体得到休息的，这就象你睡着时身体所持的样子一样。不过，鱼儿睡觉时睡的并不像你习惯上睡的那样熟，水里一有轻微的晃动，它就会被搞醒的。