Effect of rest deprivation on motor activity of fish.

The rest-activity behavior of two fish species, Cichlosoma nigrofasciatum and Carassius auratus kept under 12-h light-12-h dim condition was investigated. Rest and activity were determined from continuous time-lapse video recordings. Three states were discriminated based on the degree of motor activity. Both species exhibited a clear rest-activity rhythm with activity predominating during the light period. 'Rest deprivation' was carried out in perch during the habitual dim period by exposing the animals to either 12 h continuous light or to 6 h intermittent light (1 h light - 1 h dim for 12 h). Both light schedules enhanced activity and reduced rest. Light-induced activation was followed by an increase in low activity and rest behavior which prevailed for 12 h following continuous light, and for 6 h following intermittent light. The results indicate that homeostatic mechanisms are involved in the regulation of rest and activity in fish. These mechanisms may be similar to those underlying sleep regulation in mammals.