Figure 2.

Fractal dimension analysis of the complex swimming trajectories of adult zebrafish in control undisturbed zebrafish, in zebrafish anaesthetized but given no treatment, and in zebrafish given a fin clip, fin clip with pain-relief (PIT tag inserted in the abdomen), or subcutaneous injection of 1, 5 or 10% acetic acid yield values ranging from normal (1.15) to low (0.83), demonstrating a reduction in complexity in response to stressful or painful treatment, with arbitrary points indicating the impact of stress and mild, moderate (mod.) and severe pain. (Reproduced from [58] under Creative Commons Attribution License CC BY 4.0.)