Effect of Krill Oil Supplementation and Stocking Density on Growth Performance, Proximate Composition, and Organo-somatic Indices of Cyprinus carpio

This study was conducted to investigate the effects of krill oil supplementation on growth performance, proximate composition and organo-somatic indices of Cyprinus carpio, reared in a recirculating aquaculture system, at different stocking densities. Four experimental diets were formulated: LD - low density (15 fish/rearing unit- 3.5 kg/m3), where fish were fed with commercial feed, HD - high density (35 fish/rearing unit-8 kg/m3 fed with commercial feed), LD-KO - low density, where fish were fed with commercial feed supplemented with 5 g/kg feed krill oil, and HD-KO- high density, were fish were fed with commercial feed supplemented with 5 g/kg feed krill oil. After 60-days of rearing, final fish weight and individual weight gain was significantly higher (P˂0.05) in fish stocked in lower density, with better values in LD-KO groups. Also, the best values of FCR, SGR and PER were obtained in LD-KO groups. Regarding the proximate composition of meat, no significant differences (P˃0.05) were registered between the experimental variants. The organo-somatic indices revealed no significant differences (P˃0.05) in the cardiosomatic index, while hepatosomatic, splenosomatic, and visceral index differed significantly (P˂0.05) between the experimental variants. Accordingly, we can conclude that supplementation of carp diet with 5 g/kg feed krill oil can improve growth performance, without any modification at proximate composition of meat.