An analysis of feeding activities of sea bass (Dicentrarchus labrax, Moronidae), raised under different lighting conditions. <B>An analysis of feeding activities of sea bass (Dicentrarchus labrax, Moronidae), raised under different lighting conditions.</B><P> M. ANTHOUARD(1), M. KENTOURI(2) & P. DIVANACH(3)</B><B><P> Abstract</B><P> The effect of lighting conditions on food intake and temporal distribution of feeding activities was studied in sea-bass, by continuously recording instrumental activities of the fish raised in a self-feeding situation. Observations were made from January to May on three populations of 25-month-old fish, maintained under natural local water conditions and exposed to three lighting conditions: natural, continuous light, and continuous darkness.<P> This analysis, based upon 26 354 records of feeding activity for 136 consecutive days, indicates that daily food intake, daily biomass weight variation, and the conversion index are not different in the three lighting conditions. <I>Dicentrarchus</I>, which does not have an endogenous rhythm, appears to use senses other than vision to locate the instrumental bar and food. During the ultradian cycle, increased feeding in subjects tested under natural lighting conditions was sometimes associated with light transition (at dawn and dusk); however, it was always associated with micro-thermal elevations of the water, regardless of lighting conditions. These micro-elevations seem a more important synchronizing factor for food intake in fish.<B><P> KEYWORDS:</B> Circadian rhythm; Food intake; Self-feeding; Lighting conditions; Thermal synchronization factor; <I>Dicentrarchus labrax.<P> (1) Universite Louis Pasteur, Laboratoire de Psychophysiologie, Strasbourg, France.<BR> (2) Universite de Crete, Departement de Biologie, Iraklion, Crete, Grece.<BR> (3) lnstitut de Biologie Marine de Crete, Iraklion, Crete, Grece.</I><P> Ichtyophysiologica Acta, 1993, <B>16, </B>59-73<P>