Daily behavior and hormone rhythms in gilthead sea bream synced to light and feeding times

Gilthead sea bream exhibited 78% nocturnal feeding activity when fed at night and 81% diurnal feeding activity when fed during the day under a 12:12 h light-dark cycle.

• Feeding behavior was synchronized with the feeding phase, influencing daily activity patterns.
• Locomotor activity remained mostly diurnal (66-71%), regardless of the feeding schedule, and became arrhythmic under constant light conditions.
• Cortisol levels peaked at different times depending on the light and feeding schedule, with one peak occurring several hours before feeding during both day and night feeding.
• Glucose levels showed low-amplitude variations without identifiable daily rhythms.
• Melatonin demonstrated a nocturnal rhythm regardless of feeding schedule, but this rhythm was reduced under constant light conditions.

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