The effects of small but abrupt change in temperature on the behavior of larval zebrafish

The zebrafish has become increasingly utilized in behavioral neuroscience, psychopharmacology, and behavior genetics research. However, little attention has been paid to the potential effects of environmental conditions fish are exposed to before and during behavioral testing. One such important factor is temperature, more specifically, the difference in temperature between holding and test tanks. In the current study, we bred and raised zebrafish of the AB strain in 28 degrees C water for 7 days until they were free swimming. On the 7th day we placed each experimental subject singly into the testing well with water set to 24 degrees C, 28 degrees C or 30 degrees C for 15 min and recorded the behavior of the subjects. We found significant and behavior-specific idiosyncratic effects of the employed temperature changes. For example, lowering the temperature decreased speed, but increasing the temperature did not alter it. Increased temperature reduced duration of immobility and reduced absolute turn angle, but lowered temperature did not alter these behaviors. While lowered temperature, and to a lesser degree also increased temperature, reduced intra-individual temporal variance of absolute turn angle. Furthermore, we found no change in thigmotaxis and frequency of immobility by either temperature change. Our results demonstrate the importance of temperature in behavioral studies with zebrafish and suggest that equating water temperature between holding and testing tanks is required to enhance reproducibility and replicability of results with this species.