Table 1.

Description of stressful stimuli used during the stress treatment. Stressors were given three times per day during 23 days. Three stressor types were randomly chosen daily in order to maintain unpredictability. Modified from Madaro et al. [12].

stressful stimulielapsed timemethodology
hypoxia5 minlowering the water's oxygen saturation to 40% by closing the intake of water flow
low water level5 minlowering water level to a total of 3 cm depth while maintaining a constant flow of water
cold shock120 mindecreasing the water temperature from 12°C to 4°C
heat shock120 minincreasing the water temperature from 12°C to 19°C
aberrant noise5 minhitting the tank repeatedly with a metal bar
flashing light5 minsubjecting all fish to an intermittent flashing light under total darkness (i.e. ambient lights were turned off)
chasing5 minusing a net to stir the tank simulating a chase
netting and air exposure3 minnetting fish and exposing them briefly to air (±1 s) before release