Growth and feeding responses of juvenile red porgy to restrictive self-feeding regimes

The feeding behaviour and growth performance of red porgy subjected to restrictive self-feeding regimes (diurnal, nocturnal) were compared to those of fish given free access to feed. Fish were held at two densities (50 or 100 fish per tank) and studies were carried out at different seasons (summer-autumn-winter-spring). The fish were held in 500-1 tanks under ambient conditions and were fed by means of electronic self-feeders, connected to a computer that recorded their activation. Neither feeding regimes nor fish density had marked influences on mortality, specific growth rate, feed efficiency or body composition, except for summer, when night feeding and low density lead to increased mortality and decreased growth. Within the first 10 days of exposure to restrictive feeding conditions, the fish learned to activate the self-feeders mainly within the hours that food was available, and by the end of each 8-week period, activation of the self-feeders was limited to the hours of food availability. As a consequence, meal timing did not have any significant influence on the growth of red porgy.