Aquaculture Nutriton 2017; 1–8 wileyonlinelibrary.com/journal/anu | 1 © 2017 John Wiley & Sons Ltd Received: 21 December 2015 | Accepted: 8 July 2016 DOI: 10.1111/anu.12483 Abstract Common carp, Cyprinus carpio (13.54 ± 0.48 g), were fed soybean lecithin-incorporated diets for 8 weeks. Afer the feeding trials, the diferent groups of fshes were assessed by survival, growth parameters, digestve enzymes, antoxidant enzyme actvites, mucosal immune parameters, etc. The lecithin-incorporated diets (10–30 g kg –1 ) helped to increase the weight gain signifcantly (p < .05) compared with control groups; actvity of digestve enzymes was also signifcantly (p < .05) higher compared with experimental groups. The antoxidant enzymes including catalase and serum superox- ide dismutase were signifcantly (p < .05) higher in the C. carpio fed lecithin-incorporated feed than the ones fed the control feed. The serum thiobarbituric acid-reactve sub- stances and serum glutathione peroxidase actvity did not difer signifcantly (p > .05) between control and experimental groups. The positve correlaton supported that antbacterial actvity was signifcantly (p < .05) increased with increasing concentraton of lecithin in the diets. Among the diferent mucosal immune parameters, lysozyme, protease and esterase actvites were signifcantly (p < .05) increased with lecithin- incorporated diets. The results of this study confrm that 20 and 30 g kg –1 lecithin inclusion in diets helped to enhance the actvites of digestve enzymes, antoxidant enzymes, antbacterial factors and mucosal immune parameters in C. carpio. KEYWORDS antoxidants, Cyprinus carpio, digestve enzymes, mucosal immune responses, soybean lecithin 1 Department of Aquatc Animal Health and Diseases, Iranian Fisheries Science Research Insttute (IFSRI), Agricultural Research Educaton and Extension Organizaton (AREEO), Tehran, Iran 2 Department of Fisheries, Caspian Sea Ecology Research Center, Farah-Abad, Sari, Iran 3 Department of Fisheries, Bandar Abbas Branch, Islamic Azad University of Natural Resources, Bandar Abbas, Iran 4 Centre for Marine Science and Technology, Manonmaniam Sundaranar University, Rajakkamangalam, Kanyakumari, Tamil Nadu, India Correspondence Thavasimuthu Citarasu, Centre for Marine Science and Technology, Manonmaniam Sundaranar University, Rajakkamangalam, Kanyakumari, Tamil Nadu, India. Email: citarasu@gmail.com ORIGINAL ARTICLE Efect of dietary soybean lecithin on growth parameters, digestve enzyme actvity, antoxidatve status and mucosal immune responses of common carp (Cyprinus carpio) M. Adel 1 | M. Gholaghaie 2,3 | P. Khanjany 3 | T. Citarasu 4 1 | INTRODUCTION Common carp, Cyprinus carpio, is an important cultvable commer- cial freshwater fsh throughout the world (Eddy & Underhill, 1974). Annual world producton of carp species is around 3,000,000 tons and European producton 1,45,000 tons (FAO 2012). Carps represent the largest group of cultured fsh consttutng around 70% of freshwater aquaculture producton (Jan Mráz, 2011). Of the total world carp pro- ducton, 95% was cultured from Asia in 2001. In this region, there are more than 20 main natve carp species, contributng about 80% of the total freshwater fsh producton (Dey et al., 2001). Carp culture might be capable of becoming net producer of highly unsaturated faty acids EPA and DHA by selectng fsh with high enzyme actvites in faty acid elongaton and desaturaton. It was reported that carps, in contrast to marine fsh, are be able to bioconvert ALA to EPA and DHA (Zheng et al., 2004). Feed of plant origin has big potental for wide applicaton in fsh feed industry, and they are a cheaper source of high-quality proteins compared with proteins from animal sources (Francis, Makkar, & Becker, 2001). Soy meal is the most important feed ingredient of plant origin in the fsh feed industry. It is a source of biologically valuable proteins that are very similar in the struc- ture of amino acids to proteins of animal origin (Watanabe, 2002). Fish require relatvely high levels of crude protein in their diets as