Goldfish Tails and Circulation

To witness blood flow in arterioles, venules and capillaries, my students view the transparent tails of living goldfish under the microscope.

We use medium size feeder fish for this lab.  Students create a bed of wet gause on half of a petri dish.  Situating the goldfish with the tail off of the gause, students weigh down the goldfish with a wet blanket of gause. The goldfish tail is then flattened using a half piece of a microscope slide. The students will then view the tail of the goldfish under the microscope to view the blood flow through the circulatory system of the goldfish.

Students can distinguish between blood flow in arteries and veins.  With a little patience and effective microscopy skills they can determine the heart rate of the fish by counting the pauses in the blood flow through the venules.  Most importantly students can witness cell movement through the capillaries as single cells line up and flow through the capillaries for diffusion between the tissues.

 Students took this video utilizing a Flip cam through the ocular of the microscope.