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This science fair project for 5th graders, requires time to observe the behavior of the fish before starting the experiment. Additional time is also required to condition the fish to a new feeding schedule.
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Organisms often follow a pattern or rhythm in their behavior. Birds migrate at a certain time of the year, while many animals sleep by day and are active by night. Many people can tell when lunch time has arrived without looking at a clock. Can fish do the same? This is the subject of this interesting zoology science fair project.


Identify patterns of behavior in fish and establish whether it is possible to modify these patterns of behavior.


The biological clock, also known as the circadian rhythm, is an aspect of living organisms that regulates daily activities such as eating and sleeping. In plants, the biological clock tells the plant when to bloom or sprout. Can aquarium fish anticipate feeding time? What happens if the feeding time is changed? Can their biological clock be altered? Refer to the bibliography section for more information on biological clocks.

Scientific Terms

Biological Clock,


  • Aquarium fish (eg. gold fish)
  • Aquarium
  • Fish food
  • Timer


  1. To prepare for this cool science project, observe your fish daily to familiarize yourself with their swimming patterns. Does the fish tend to occupy certain parts of the tank more so than others?
  2. Create a feeding schedule whereby you feed your fish each day at the same time of the day.
  3. After a period of 1 week approximately, notice where the fish positions itself within the tank during feeding time.
  4. Continue for another 3 days, observing the fish's location at feeding time. Is the fish demonstrating a consistent pattern of behavior at feeding time?
  5. On day 4, change the feeding time. Observe the fish daily, both during the old feeding time and the new feeding time. How long does it take before the fish adjust to the new feeding time?


How does your biological clock affect your life?

Questions & Answers

What is the biological clock?

The biological clock is an internal process that regulates biological activities such as eating or sleeping.

Make it Your Own

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