#F 423 Project Summary Title: What concentration of sodium fluoride affects zebrafish behavior? Purpose

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#F 423

Project Summary

Title: What concentration of sodium fluoride affects zebrafish behavior?

Purpose: To find out at what concentration of sodium fluoride would cause zebrafish to behave irregularly.

Hypothesis: I think zebrafish behavior will change at 5mg/L of sodium fluoride in their tank. The behavior that I’m looking for is aggressive behavior (for example, attacking a mirror).


Fluoride is used in toothpaste to protect your teeth from the acids that could damage your teeth. The acids are caused by bacteria in your mouth and the sugars that you eat. In some places, fluoride is added to drinking water to prevent tooth decay. Several studies done in the 1930’s found that water with natural fluoride had up to two thirds fewer cavities as to those who did not have fluoride in their water. But also, too much fluoride can give people headaches, stomach aches, vomiting, cancer, and many other problems. Kids under 6 years old and their teeth are growing have problems when they have too much fluoride. Their teeth will turn brown and hard to clean. For aquatic animals, a study has shown that 0.2mg/L of fluoride is toxic and affect the migration of some salmon species.

Zebrafish (Danio rerio) are a great animal model to use for experiments because they have short life cycles, their behaviors are easy to observe, and their embryos are transparent during development. Their genes are fully sequenced and are used many genetic studies.

I will use zebrafish to test at what concentration of sodium fluoride that will cause them to behave differently. The concentrations that will be tested are 0, 1, 5, 75, 100, 200, and 400 mg/L. Scientists studied aggression in zebrafish by putting a mirror on one side of the fish tank. The male zebrafish will attack the mirror because it sees another male and shows its aggression and territorial nature.


Sodium fluoride



Small container with lid

Air pump

Fish tank

Fish net

Dechlorinated water


3D tracking device


  1. Ask an adult to weigh out sodium fluoride at 0, 1, 5, 75, 100, 200, and 400 mg.

  2. Fill a small container with 1 L of dechlorinated water.

  3. Put sodium fluoride in each container and mix it well.

  4. Scoop 1 male zebrafish with a net and put it in each container of sodium fluoride and wait for 24 hours.

  5. After 24 hours, add dechlorinated water to a fish tank and transfer the fish from the container to the fish tank.

  6. Place the fish tank inside a 3D tracking device.

  7. Put a mirror behind the fish tank.

  8. Turn on the 3D tracking device and track the fish for 5 minutes.

  9. Collect and analyze data.

  10. Repeat steps 1-9 at least 3 times.


A frame from the 3D camera shows a male zebrafish attacking the mirror.

zebrafish 1.jpg

A frame from the 3D camera shows a male zebrafish NOT attacking the mirror.


This is a path of a zebrafish swimming in the fish tank after 5 minutes of tracking at different concentrations of sodium fluoride. The mirror is placed on the left side of the tank. A male zebrafish that attacks the mirror in these kinds of experiments shows aggression.

new-0mg-a.tif new-0mg.tif 0 mg/L

1-mg-a.tif 1mg.tif 1 mg/L

5-mg-a.tif 5mg.tif 5 mg/L

50-mg-a.tif 50mg.tif 75 mg/L

100mgl-1a 100mgl-1 100 mg/L

200a 200b 200 mg/L

400a 400b 400mg/L


The data from the 3D tracking device showed that 200mg/L of sodium fluoride and at higher concentration, the zebrafish behavior changed. They were no longer attacking the mirror. The zebrafish with no sodium fluoride or less than 200mg/L attacked the mirror more often in the 5 minutes of tracking, which is a sign of aggression for their natural behavior. My hypothesis is wrong and the concentration of sodium fluoride that would affect the zebrafish is much higher than what I predicted.


Wikipedia on zebrafish and sodium fluoride

JOVE – Using an Automated 3D-tracking System to Record Individual and Shoals of Adult Zebrafish

Impact of Fluoridation on Fish (www.ffo-olf.org)


I would like to thank Dr. Hans Maaswinkel for assisting me during this project.

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