Can Fish Tell Time?
How does your biological clock affect your life?
What is the biological clock?
The biological clock is an internal process that regulates biological activities such as eating or sleeping.
Repeat this interesting experiment with a group of fish, or try changing the lighting of the aquarium. Make the aquarium dark during day time and bright during night time.
"What is your biological clock?" at the Essortment web site http://www.essortment.com/biological-clock-58165.html