Sleeping with the fishes

Fish don't have eyelids, but they definitely sleep.

In the morning and evenings when people are around, the goldfish are active. They swim around and play with each other and try to showboat to get some extra food.

But when no one is here during the day time, they get their rest. I just found them quietly floating together at the bottom of the tank away from the bubble stone and filter cascade.

The flash from the camera woke them up, but they seem to have gone back to sleep now.

I need to change the filter and a quarter of the water this weekend.