Effect of microalgal based diets on growth, proximate, fatty acid and amino acid composition of water flea (Daphnia magna)

Abstract

Water flea (Daphnia magna) is used as live prey for freshwater and marine aquaculture species. They are also utilized as protein source in formulated diets. The culture success of zooplankton production is mainly depend on diets. The nutritional value of Daphnia magna is very important for larval and juvenile fish nutrition and this affect the survival and growth of fish. In this study, two fresh microalgae Euglena gracilis (EG) and Pavlova lutheri (PL) and four commercial dried microalgae products Algome® (dried Schizochytrium sp.), Naturiga® (dried Spirulina platensis), ProteinPlus® (PP) and AlgomeGrow® (dried Chlorella sp.) were evaluated for Daphnia magna culture. Survival, growth, fatty acids, and amino acid contents of daphnia have been studied. Higher survival supported by ProteinPlus diet (68%) and growth performance improved by utilization of fresh microalgae Euglena gracilis. Crude lipid content was increased by Algome® (8.91%) and ProteinPlus® (8.77%) diet whereas highest crude protein was obtained by Naturiga® diet (55.66%). Daphnia fed Algome® showed the highest DHA accumulation in daphnia body whereas EPA level was enhanced by ProteinPlus diet and ARA level were only supported by Naturiga® diet. There was detected a strong correlation between certain fatty acid groups (Oleic acid, α-linolenic acid, Ʃ n-3, and Ʃ n-3 HUFAs) and diets. AlgomeGrow diet enhanced whole essential amino acid contents of daphnia at the end of the experiment.