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The behaviors of organisms will be repeated if such behavior results in a positive outcome. When behavior does not result in a positive outcome, such behavior will diminish. The male betta fish displays a certain behavior of warning other males to stay away. This science fair project will allow you to observe what happens when the betta's "warning" behavior stops working, which can be caused by extinction or habituation.


Understanding habituation and extinction of aggressive behavior.


Bettas are very territorial fish. Also known as Siamese fighting fish, males have elaborate display behaviors that they use against other male bettas. The display behavior serves as a warning to other fish. If displaying does not work, bettas will attack an intruding fish. This territorial behavior has endured in this species because it has proven to be an effective deterrent. But what happens if a behavior does not yield the expected results? When a behavior is not reinforced by a positive outcome, the behavior will diminish with time. This is called extinction. Habituation is when an organism gets accustomed to a stimulus and no longer responds to it. You may get irritated by something at the beginning, only to get use to it with the passage of time. You will observe how the displayed behavior of the betta fish is affected by both extinction and habituation. View the following resources for specific information on betta display behavior and care.

Scientific Terms

Betta, Habituation, Extinction


  • Betta fish and fish supplies
  • Mirror
  • Data Sheet (Provided).


Day 1

  1. Place a mirror in front of the aquarium glass so the betta can see it.
  2. Observe the reaction of the betta. The betta should display aggressive signs (Refer to "Betta Splendens Aggression," located in the bibliography section).
  3. After the betta displays aggression, remove the mirror. Wait for 1 minute then present the mirror again and observe the betta's reactions, paying attention to any changes in the display behavior.
  4. Repeat this process until the betta shows little or no interest when presented with the mirror. Make sure to note the number of trials so that it may be entered in the data sheet. Each time you present the mirror is one trial of the science experiment.
  5. Record the number of trials in the data sheet.
  6. Discontinue the experiment till the next day.
  7. Create a hypothesis of what you think will happen the following day when the betta is retested. Write your hypothesis as " If I repeat the experiment on the second day, the betta will take ______less, more, or the same number___ of trials before it's response to the mirror diminishes.

Day 2:

Repeat your science project experiment and record data. Compare the results of day 1 and day 2. Were the findings of day 2 consistent with your hypothesis?

Betta Display Behavior Data Sheet

Day 1

Day 2

Number of trials before displaying behavior fades


What are examples of extinction or habituation in your own thoughts or behaviors?

Questions & Answers

What is the purpose of the betta's display behavior?

To warn intruders.

How is the betta's display behavior reinforced?

If the intruder retreats, then the display behaviors of the betta will be repeated in the future.

Make it Your Own

Obtain another male betta and put it in a glass bowl. Put this bowl next to the bowl of the fish you conducted your science experiment with. Compare the betta's display behavior to the new fish with that of its own reflection.