Zebrafish Rheotaxis Assay: A Method for Measuring Orientation Behavior in Response to Different Water Flow Rates

- First, carefully transfer the fish to the swimming tunnel and switch on the water pump. Let the fish acclimate for one hour to reduce its stress level. Fish tend to display positive rheotaxis or orienting upstream in flowing water. Using video analysis and a modeling software program, track the time and fish movement by marking its eye position at each upstream to downstream turn with a dot, and at each downstream to upstream turn with dot of a different color. Increase the water flow rate and repeat the trial. We can calculate a rheotactic index by comparing the time spent facing upstream to the total, thereby, quantifying the fish's orientation behavior. The example protocol is part of an experiment to separate the influences of water flow and magnetic fields on the orientation behavior of fish.

- To set up a magnetic field with one dimensional magnetic field manipulation, keep the tunnel open and switch on power unit and magnetometer. Place a magnetic probe connected to a gas Tesla meter inside the tunnel and verify the voltage necessary to obtain the chosen magnetic field value along the major axis of the tunnel. Then disconnect the probe and connect the flow tunnel to the sw