The effect of temperature on the spatial learning rate of zebrafish (Danio rerio)

Abstract

Temperature has a wide range of effects on the biology and ecology of ectotherms, including fish. However, the literature provides only a few studies assessing its effect on their cognitive abilities. We tested the effect of temperature on the spatial learning rate of zebrafish by comparing the daily rate of change in the number of fish choosing the correct arm first and behavioural performance (i.e., distance travelled, time needed to locate the daily food reward and swimming speed) in two temperatures (21 and 31°C) in 7 successive sessions. The daily rate of change in behavioural performance was expressed as the percentage difference between the value in a given session and the value in the previous session. Two experiments were performed in a T-maze with single feeders in the arms, one empty and the other with a food reward. In each of the experiments, we used 10 naive fish, which were placed in the T-maze individually once a day. The fish were fed between sessions to avoid increasing differences in hunger levels and, in turn, increasing the differences in motivation to find the food between the temperature treatments. The results revealed that the learning rate was greater at the higher temperature, which was apparent in a greater percentage reduction in the time and distance travelled needed to locate the daily food reward between successive sessions at the higher temperature than at the lower temperature. The results show there was a significant effect of temperature on the daily rate of change in the number of fish choosing the correct arm, distance travelled and time needed to locate the daily food reward, which may be attributed to the positive effect of temperature on learning rate, and may indicate the importance of temperature for the cognitive testing of zebrafish.