Water Quality - Unit 2


Purpose: The purpose of this experiment is for students to gain experience in altering the temperature water and to observe how goldfish respond to different temperatures in their environment.


    • 3- goldfish
    • 3 - 1000mL beakers
    • 3-Thermometers
    • 2-Large plastic tubs (37 cm x 31 cm)

Note: Read all of the instructions before proceeding!!


1. Make predictions on what will happen to the fish in the Hot and Cold environments.
    1. What is the expected behavior of the fish in the colder water?
    2. What is the expected behavior of the fish in the warmer water?


2. Place the Hot beaker in the tub of hot water and the Cold in the tub of ice water. The water in each tub should be at a level high enough that most of each beaker is submerged. The third beaker is to be left at room temperature (this is the Control beaker).

3. Place a thermometer in each beaker. Stir each beaker, making sure all of the water in the beaker has a uniform temperature. You can use the thermometer to stir the water, but remember to check the temperature of the water periodically. When the temperature approaches the indicated range for each beaker, you will have to watch the temperature more closely to know when to take the beakers out of the tubs.

          4. The desired temperatures for each beaker are:

    • the Control beaker’s temperature should be between 20-25 º C
    • the Cold beaker’s temperature should be between 10-12 degrees º C
    • the Hot beaker’s temperature should be between 37-40 degrees º C.

5. When the water in the beakers reach these temperatures, remove them from the tubs of ice water and hot water. Record the exact temperatures of the water in each beaker.

Note: This may take 20-30 minutes because water takes a long time to reach the desired temperature. Make sure that the water in the beakers have stabilized at this temperature; begin observations as soon as you remove the beakers from the hot and cold water baths.

6. Place one fish each in the Control beaker, the Cold beaker and the Hot beaker once the temperature of the water in the beakers has stabilized and as soon as possible following removal of the beakers from the water baths!!



7. After 20 minutes have elapsed, make observations on the behavior of the fish. Is there a marked difference in the speed that they move? Is their behavior different? Is there a difference in their physical appearance?

          8. Pick one of the following physical movements to monitor in every goldfish:

    • swishing of tail
    • flexing of mouth
    • flexing of gills

Each of these movements are done by the goldfish at a measurable rate in a normal environment.

9. One student should count the goldfish’s movements in the Control, Hot and Cold beakers and one group member should serve as the timer. Count the number of times the goldfish makes this movement over the period of 1 minute. Record the rates and compare them.

10. Compare your results with what you predicted. The results will be based on any physical changes observed. Are the results the same as your predictions or are they different? Is the behavior of the fish in the hot and cold water different from the control group?