My Favorite Fish Lab

Two years ago, I was planning to do a lab with the heart rate of Daphnia. I had the lab form all prepped for my students, but then realized that I didn't have enough time to order the Daphnia. I went to Google for some ideas and found some great experiments with goldfish (AKA feeder fish). Those I could go to Petsmart for and they only cost $0.14-$0.29. One of the labs I found was the Fish Temperature Lab from Biology Corner, and others from Laying the Foundation, Inc., and a lab by David L. Umbarger in Montezuma-Cortez High School, Cortez, CO, So, for the last two years, we've been doing a lab with goldfish (feeder fish) in both regular Biology and AP Biology that is a combination of these labs.  We only have a few modifications in the lab between the two levels of classes. In this one lab, we tie in the concept of endo/exothermy, the respiratory system, and the circulatory system.  Last year, we also tried a tie in with the endocrine system, although it was difficult to notice results.

We start the lab by putting a fish in a beaker and then putting the beaker in a water bath. We measure the respiration rate either by counting the opening of the fishes' mouth or the movement of the operculum. Students add warmer water to the bath and continue to measure respiration rate. After we finish with the slightly warmer temperatures, we add ice cubes to the water bath and continue to measure "breaths" as the temperature decreases.

For my regular Biology class, this provides great graphing practice as they gather and find the class average and graph the results.  In AP Bio we use this as an opportunity to talk about determining Q10 for fish respirations and talking about what that means.

After giving the fish some time to reaclimate to aquarium temperature, we move onto the next part of the lab. Actually, we usually set those fish aside to allow them to reaclimate and use the fish we didn't use in part one. Each year I've done this lab, I've had to convince students that we won't kill the fish we use in part 2. For part two, we wrap the fish in aquarium water soaked cotton and look at their tails under the microscope. Students are amazed once they see the blood vessels in the fish tails with blood cells actually moving through them.

Last year, in part 2 we then added dilute adrenaline to the fishes' tails to observe the affect, but we had a hard time noticing a difference. We talked about the expected results (faster blood flow) and what the actual results should have been (slower blood flow since the tail is an extremity).

I am happy to report that both years we've done this, all of the fish have survived.

Here's the lab form that I give my AP Biology class. Here's the form I give to regular Biology. I also give them directions separately to save me some photocopies.