Effect of fish meal replacement by Azolla meal on growth performance, hemato-biochemical and serum parameters in the diet of scale carp, Cyprinus carpio var. communis

A 12-week growth experiment was conducted to evaluate the suitability of Azolla cristata as a fish meal (FM) substitute in diets for Cyprinus carpio var. communis fingerlings. Six iso-nitrogenous and isocaloric (16.17 kJ/g GE) diets were formulated to contain 42% crude protein and each treatment had three replicates. The mean initial weight of the fish was 3.4 ± 0.2 g. Graded levels of A. cristata 0, 10, 20, 30, 40, and 50% in the diets were fed to the fish in triplicate groups, respectively. No significant (p > 0.05) differences in growth performance of fish-fed diets containing 10% and control (0%) inclusion levels were seen. However, further increase in Azolla meal (AM) supplementation resulted in gradual decline in growth performance of fish in terms of live weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio. All hematological parameters had a linear declining trend as the proportion of AM in diet was increased. Protein content of fish was found significantly (p < 0.05) reduced in fish-fed higher inclusion of AM. Serum biochemical parameters were also noted to reduce with increasing inclusion of AM, except for glucose, cholesterol, alanine aminotransferase (ALT), and aspartate aminotransferase (AST). On the basis of results obtained in the present study, it is recommended that 10% Azolla meal can be included in the practical diets for C. carpio var. communis fingerlings as partial replacement for fishmeal without affecting their growth, feed efficiency, and fish quality for the intensive culture of this fish species.