Figure 2.

Behavioral testing procedures. The procedures for the behavioral tests of locomotor activity, thigmotaxis, and behavioral response to light change consisted of four steps: a 20 min acclimatization phase, the first light phase (minutes 0–10), a dark phase (minutes 10–20), and the second light phase (minutes 20–30) (A). The tests of the above behaviors were performed in a dish (diameter of 90 mm). The inner and outer zones were delineated as shown above. The width of the outer zone was set at 13 mm to the border of the dish (B,C). The social preference was tested in a rectangular chamber. The fish being tested was placed in area “a,” and six companion zebrafish were placed in area “b” (D). “a” was the test area (70 × 42 mm) and was equally divided into one proximal zone and one distal zone (E).