Fig. 1

Diagram of behavioural apparatus for olfactory conditioning in home tanks. Panels A and B illustrate representative positions of experimental fish before and during the presentation of conditioned stimulus, respectively. In (A), the approximate mean position of the group of fish (centroid; *) is near the center of the tank. Water enters via a tube on the top left of the tank and exits on the right. In (B), the centroid is in Quadrant 1 (Q1), where the odour (phenylethyl alcohol; PEA) is dispensed via tube. A red LED indicated to the camera when the odourant is being delivered. Then, 15 seconds later, food is dispensed by the automatic feeder located above the tank. A plastic baffle keeps the food contained in Q1. In (C), a timeline of a single trial is presented. The video starts and 15 seconds of behaviour is recorded. Then, the odour is dispensed as indicated to the camera with the LED light. After 30 total seconds the video ends and then the experimental fish are fed, while control fish are fed at a later time in between trials. For the analysis, a latency period of 5 seconds was noted between the addition of the odour and the behavioural response of the fish. Therefore, only the last 10 seconds of the video was analysed.