Different fish species employ a conditional approach strategy during predator inspection; the risk of approaching a predator is distributed across all inspectors, but is not shared with the animals which keep its distance. Zebrafish, a highly social fish, is increasingly being used in behavioural neuroscience, but it is not known whether it displays conditional approach. In the predator inspection task, animals are observed in a tank with a refuge in one extremity, and an animated image of a predator in the other extremity, with a mirror positioned in parallel to the tank, simulating a perfectly reciprocating conspecific. In Experiment 1, animals spent more time in an inspection zone when the image was turned on, but also displayed more erratic swimming, suggesting cooperation under fear. In Experiment 2, animals spent more time inspecting predators when the mirror was parallel to the tank ("cooperating mirror") than when the mirror was in an angle ("defecting mirror"), suggesting retaliatory behaviour; in both conditions, animals displayed more freezing and erratic swimming. In Experiment 3, no changes in behaviour were observed, regardless of mirror position, when the image was turned off, suggesting that the choice of specific zones in Experiment 2 was not due to shoaling tendencies. These results suggest that predator inspection is associated with conditional approach, while at the same time inducing fear-like behaviour in the animal.

中文翻译：

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斑马鱼在检查捕食者的同时进行合作：条件方法的实验证据

不同种类的鱼类在捕食者检查过程中采用有条件的进近策略；接近捕食者的风险分布在所有检查人员中，但与保持距离的动物没有共同承担风险。斑马鱼是一种高度社交的鱼，越来越多地用于行为神经科学中，但尚不清楚它是否显示条件性方法。在捕食者检查任务中，在一个四肢带有避难所的水箱中观察动物，而在另一肢中则有一个捕食者的动画图像，镜子平行于水箱放置，模拟了完美往复的同种动物。在实验1中，打开图像后，动物在检查区域停留的时间更长，但游泳也更加不稳定，这表明他们在恐惧中合作。在实验2中，当镜子与水箱平行时，动物花费更多的时间检查掠食者（“协作镜子”），而不是当镜子倾斜时（“缺陷镜子”），这表明报复行为；在这两种情况下，动物都表现出更多的冰冻和不稳定的游泳。在实验3中，关闭图像后，​​无论镜子位置如何，均未观察到行为变化，这表明实验2中特定区域的选择不是由于暗流趋势造成的。这些结果表明，捕食者的检查与有条件的方法相关联，同时又诱发了动物的恐惧样行为。在这两种情况下，动物都表现出更多的冰冻和不稳定的游泳。在实验3中，关闭图像后，​​无论镜子位置如何，均未观察到行为变化，这表明实验2中特定区域的选择不是由于暗流趋势造成的。这些结果表明，捕食者的检查与有条件的方法相关联，同时又诱发了动物的恐惧样行为。在这两种情况下，动物都表现出更多的冰冻和不稳定的游泳。在实验3中，关闭图像后，​​无论镜子位置如何，均未观察到行为变化，这表明实验2中特定区域的选择不是由于暗流趋势造成的。这些结果表明，捕食者的检查与有条件的方法相关联，同时又诱发了动物的恐惧样行为。