Immune protection role and disease prevention in common carp, Cyprinus carpio (Actinopterygii, Cypriniformes, Cyprinidae) against a heterotrophic Gram-negative bacteria, Aeromonas hydrophila due to spirulina, Arthrospira platensis supplement

An eight-week feeding trial was conducted to evaluate the effect of the fish meal, soybean meal and squid meal were replaced by spirulina on growth, survival, immune protection and disease prevention in Cyprinus carpió against Aeromonas hydrophila infection. Six different experimental diets were prepared which includes a control diet (D1) and 5 different composition (5, 10, 15, 20 and 25%) of spirulina Arthrospira platensis diets (D2 to D6) where spirulina replaced the fish meal, soya meal and squid meal. The cumulative mortality was calculated as 27, 19, 14 and 11% in the fish groups received 10, 15, 20 and 25% spirulina respectively; and significantly (p < 0.05) high mortality (92%) was noticed against the pathogen in the fish fed control diet. The immunological assays namely, phagocytic, respiratory burst and complement activities were significantly (p < 0.05) increased in the individual fed 15, 20 and 25% spirulina diets between 2 and 4 weeks of post-challenge. The lysozyme activity was enhanced significantly (p < 0.05) in fish fed all the spirulina diet compositions throughout the experiment. Overall, the findings suggested that the inclusion of spirulina at the dosage between 15 and 25% in the diet enhanced the growth, survival and defense response in C. carpio significantly (p < 0.05), which ultimately lead to disease resistance and defense protection against A. hydrophila infection.