Periodicity of reproductive behaviour by the blue tilapia,Oreochromis aureus

Synopsis Oreochromis aureus exhibits a diel periodicity of spawning when maintained on a controlled 14:10 light:dark photoperiod, with a peak in spawning activity during the 11th hour of light. That this periodicity of spawning is a response to light is supported by phase-shifting the light cycle by seven hours. This results in a corresponding shift in the times of spawning.