F. Ansarifard - Department of Fisheries, Science and Research Branch, Islamic Azad University, P.O. Box ۱۴۵۱۵-۷۷۵,Tehran, Iran.
H. Rajabi Islami - Department of Fisheries, Science and Research Branch, Islamic Azad University, P.O. Box ۱۴۵۱۵-۷۷۵,Tehran, Iran.
M. Shamsaie Mehrjan - Department of Fisheries, Science and Research Branch, Islamic Azad University, P.O. Box ۱۴۵۱۵-۷۷۵,Tehran, Iran.
M. Soltani - Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.

This study evaluated the effects of diets containing ۰, ۲.۵, ۵, ۷.۵ and ۱۰% Arthrospira platensis on skin pigmentation, growth performance, and digestive enzymes of koi, Cyprinus carpio. A completely randomized design was performed with five treatments and three replicates. One hundred and fifty koi fish with average initial weight of ۳۰±۱g were assigned to fifteen experimental tanks. The experiment lasted for eight weeks. Koi fish fed with ۲.۵% A. platensis (۱.۱۷±۰.۰۲) showed a significant lower growth performance than those fed with ۷.۵ and ۱۰% A. platensis (۱.۳۹±۰.۰۲ and ۱.۴۶) (p<۰.۰۵). However, carotenoid (astaxanthin) concentrations of skin significantly increased with increased levels of dietary algae (p<۰.۰۵). The highest values of a* (red zones) and b* (yellow zones) were observed in fish skin fed with ۱۰% A. platensis (۴.۳۳±۰.۱۵, ۵.۲۳±۰.۱۵, ۵.۲۳±۰.۱۵, ۵.۷±۰.۳۶, and ۶.۳۳±۰.۳۲, respectively). The activities of protease, amylase and lipase in dietary supplementation of ۱۰%A. platensis were significantly higher than those of the control group (protease from ۵.۱۷±۰.۷۶ to ۱۱ , amylase from ۲۲±۱.۷۳ to ۳۲.۶۷±۱.۵۳ and lipase from ۱۶.۳۳±۲.۰۸ to ۷۴.۳۳±۱.۵۳. Liver enzymes also decreased significantly by increased dietary supplementation. (ALT: from ۱۹۲.۳۳±۵.۵ to ۸۰.۶۷±۱.۵۲, AST: from ۱۷۴۱.۷±۱۸.۹۲ to ۷۱۲.۳۳±۱۰.۵, ALP: from ۴۵۲.۳۳±۸.۱۴ to ۴۸±۱, LDH: from ۷۲۸۷.۳±۳۴.۶۴ to ۷۱۱۹.۷±۱۷.۸۹). These results revealed that inclusion of ۵-۱۰% A. platensis in diets has a significant positive effect on growth rate, pigmentation, and improvement of digestive and liver enzymes activities in koi fish.

Arthrospira platensis, Pigmentation, Growth, Carotenoids, Enzymes activities, Koi