Nutrient profiling of five freshwater algae for their prospective use as fish feed ingredients

This study was conducted to appraise the nutritional potential of five commonly available and unexplored freshwater algae (viz., Cladophora, Microspora, Pithophora, Lyngbya and Spirogyra) for their sustainable utilization as a component of low-cost animal feed. Results of proximate analysis (% dry matter) revealed that the crude protein content of the algae ranged between 10.49 and 30.8 % (w/w), whereas crude fibre and ash contents varied between 11.37 and 17.56 %, and 16.32 and 20.21 % (w/w), respectively. Protein to energy ratio (P/E) of these algae ranged between 38.99 and 94.1 mg/kcal, being the highest with Spirogyra. The evaluated algae contained considerable mineral elements required for the normal growth and development of fish. Analysis of anti-nutritional factors indicated presence of varied amounts of trypsin inhibitor (0.33-0.67 mg/g), tannin (1.28-6.91 mg/g) and phytate (1.18-2.86 mg/g), which were within the tolerable limits. Antioxidant and antibacterial potentials of the algae were also documented. Further evaluation exhibited that these freshwater algae might serve as sources for some essential amino acids and poly unsaturated fatty acids. From the nutrient profiling of these freshwater algae, we suggest utilization of Spirogyra and Lyngbya for formulation of low-cost and balanced fish feeds. However, further studies involving in vivo feed evaluations are warned prior to recommend them for commercial aquaculture.