Fish that don't sleep at night?

For starters, fish don't sleep in general. Fish go into a resting period and usually that has to do with the place the sun is in or if it is a fish in a tank, whether the lights are off or on.

Secondly, some fish move all day and night to keep away from predators and to insure water is passing over there gills. A fish will move while resting, when they do they are moving slowly and lower in the tank. If you have a few small fish they will follow each other and wake each other up. (Hardy fish are the best ones).

Lastly, fish are great pets for people who are half commited pet owners!

Treat them well