ZOOTECHNICAL PERFORMANCE AND BODY-COMPOSITION OF PERCA-FLUVIATILIS PELLETED DIET IN A FLOATING CAGE - EFFECT OF DAILY RATION

Mass rearing performances and body composition of perch Perca fluviati lis (25 g) fed on a pellet diet in floating cages were studied during July to September 1993. At the end of this period, they weighed 48 to 49 g and the survival rates were 70 to 79%. The feeding rates (3 or 4% ) had no direct influence on the zootechnical potentialities or body c omposition. In September the gonadosomatic index increased, particular ly for males. Sexual maturity triggered a regression of hepatosomatic index and a modification of fish body composition. In comparison with perch bred in a closed system at 22.0 degrees C, the fish in cages had a higher protein and a lower lipid and energy content. Triacylglycero l fractions and phospholipids evolve reversely as function of the rear ing system.