koi fish do indeed sleep during the day, but their sleeping habits vary due to individual differences. Here is a detailed analysis:
The Prevalence of Daytime Sleep
Most koi fish sleep during the day as well, especially after they have eaten their fill or when there is no need for activity. They may float at the bottom of the water and swim occasionally, showing a relatively resting state.
Individual Differences in Sleep
Each koi fish has a different personality. Some fish like to sleep in a fixed place, while some fish may be more active during the day. However, even for koi fish that sleep during the day, their sleeping time is usually short, and they are easily awakened by external stimuli (such as light or food).
Differences from Nighttime Sleep
The nighttime sleep of koi fish is usually more regular and fixed, while the daytime sleep is more like a short resting state. This sleep pattern may be related to their foraging and activity habits.