Nutritional value of planktonic cladoceran daphnia magna for common carp (cyprinus carpio) fry feeding

Summary Chemical composition and contents of amino acids and fatty acids in the planktonic cladoceran Daphnia magna were investigated, aiming to evaluate its value for feeding of young carp. Crude protein, crude fat, crude fibre, ash and moisture contents were analyzed according to standard laboratory procedures. Amino acids content was determined by LKB 4101 automatic analyzer and that of fatty acids by Chrompack CP 9000 chromatograph, using a flame ionizing detector. Protein contents amounted to 1.18 and 39.24% of fresh and dry mass, respectively. These amounts of proteins completely meet nutritional requirements both of carp fry and its older categories and other omnivorous fishes. Raw fat and fibre contents in dry weight were 4.98 and 4.32%, respectively, which is suitable for the commercial carp breeding. Methionine and phenylalanine are partially in deficit, whereas other essential amino acids identified in dry mass of Daphnia magna were present in amounts adequate for all carp categories. The proportions of saturated and unsaturated fatty acids in lipids of Daphnia magna were 18.70 and 66.20%, respectively. Among the unsaturated fatty acids, the omega–3 group was present with 27.30%. The omega–3 : omega–6 fatty acids ratio was 5.68:1, which fully meets the carp nutrition requirements.