[Diurnal periodicity of wakefulness and sleep in the catfish Ictalurus nebulosus].

In studies on the behavioural reactions, cardiac rhythm, respiration and EMG in unrestrained catfish, awakefulness and two forms of rest were differentiated. It was shown that in the diurnal rhythm of these functional states, certain behavioral reactions, cardiac rate, type of respiration and EMG correspond to each of these states. By means of discrete recordings of these parameters within several days, in 15 specimens diurnal distribution of awakefulness and two forms of rest was investigated. It was found that the daily form of rest in the catfish exhibits some similarity with cataleptic-like immobilization which was observed in the diurnal activity of amphibians, reptiles and birds.