Influence of stocking density on growth of juvenile red porgy Pagrus pagrus L. under different feeding conditions

The influence of stocking density and feeding regime on the growth of red p orgy was studied during winter and spring 1997. Fish were held in 500-L tan ks at densities of either 50 or 100 fish per tank, and were fed by means of self-feeders under 6 h restricted (day or night) or free-access feeding re gimes, Fish were tagged individually, and weight gain was recorded by indiv idual weighing every second week over an 8-week period during each season. In winter, growth was influenced by feeding time. Fish tended to grow best when fed without restriction and worst when fed at night, although differen ces were not significant when tank means were compared, Stocking density wa s influential in the spring trial, Fish stocked at low density and feeding freely grew better than high-density fish that fed either freely or at nigh t. The division of fish into three size classes revealed that, within each treatment, no differences occurred among classes, but growth of fish belong ing to the same class was influenced by rearing conditions. No significant differences were found among feeding regimes in terms of the coefficients o f weight variation ratio (CVf:CV1) and feed efficiency.