Effect of dietary supplement Spirulina (Arthrospira platensis) to feed on some growth parameters and the activities of antioxidant enzyme defense in koi fish (koi, Cyprinus carpio(

In this study, the effects of different concentrations of ) Arthrospira platensis ( on the growth and antioxidant defense mechanism of koi fish (Cyprinus carpio (were investigated during a 8 weeks culture period. ). An experiment was designed with five treatments, including diets with 0, 2.5, 5, 7.5 and 10% of Arthrospira platensis and each with three replicates. One hundred and fifty koi fish with average initial weight of 30±1g were assigned to fifteen experimental tanks.The results revealed that the Superoxide dismutase(SOD) and catalase(CAT) activity level  in 10% (Arthrospira platensis) treatments demonstrated a significant increase compared to the control group (P<0.05)   and in all samples taken at different  treatments of the experiment did not show any significant differences(P>0.05). Liver enzymeze also decreased significantly by dietary supplementation (p<0.05). Also Koi fish  fed with 2.5% A. platensis showed a significant lower growth performance than those fed with 7.5 and 10% A. platensis (p<0.05). These results revealed that, inclusion of 10% A. platensis in diets did appear to have a significant positive effect on antioxidant defense mechanism , liver enzymes activities and growth rates of koi fish.