When do goldfishes sleep?

Answer 1

Fish, or goldfish anyway, never sleep. Well, they don't sleep the way we do anyway. They go into a sort of relaxed mode where they slow down but they are instantly ready to swim away if any danger appears.

Answer 2

it depends if your goldfish is nocturnal or not because some types are. goldfish sleep with their eyes open like most other fish to protect themselves from predators.