Change light gently
A room suddenly going dark or a bright lamp being switched on can make shrimp retreat. Use the aquarium’s normal light schedule and a gradual room transition where practical.
Do not leave a flashlight aimed at the tank to count animals. Repeated disturbance changes the behavior you are trying to observe.
Separate light response from water issues
A brief retreat after a lighting change is different from persistent abnormal activity. Note how long the behavior lasts and whether other conditions changed.
If multiple shrimp remain distressed, check the water, filter, and temperature rather than assuming light is the only cause.
Make observations repeatable
Use similar lighting and viewing conditions when tracking the colony. This helps you compare days without startling the shrimp each time.
If your light schedule changes, adjust it intentionally and monitor plant and animal responses. Avoid copying an exact duration without considering the tank.
Use these as general hobby references. Test your aquarium and confirm product guidance before making changes.