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The present study investigated the effects of dietary astaxanthin on the growth, blood biochemical, antioxidant, immune and inflammatory response in lipopolysaccharide‐challenged Channa argus. A total of 0, 50, 100 and 200 mg/kg of astaxanthin were added to the basal die for 56 days. After the feeding experiment, each group was subjected to a lipopolysaccharide challenge (except for the Control group). The results showed that adding astaxanthin to the diet can significantly increase the weight gain and specific growth rate and decrease the feed conversion ratio of C. argus; the highest weight gain, specific growth rate and minimum feed conversion ratio occurred in the 100 mg/kg group. Furthermore, dietary astaxanthin supplementation can alleviate the negative effects of lipopolysaccharides by increasing the levels of alkaline phosphatase, lysozyme, complement 3, complement 4, total serum protein, albumin, globulin, superoxide dismutase, catalase and glutathione peroxidase and decrease the serum cortisol, aspartate aminotransferase, alanine aminotransferase, glutathione peroxidase, and malondialdehyde. Dietary astaxanthin supplementation also can decrease the relative expression of inflammatory genes (nuclear factor κB, interleukin‐1, interleukin‐8 and tumour necrosis factor‐α) in the liver, spleen, kidney and intestine. To summarise, dietary astaxanthin addition can improve the growth performance and attenuate the negative effects of lipopolysaccharide challenge in C. argus. The optimal amount of astaxanthin is 100 mg/kg.

The aim of this study was to investigate the effects of citric acid (CA) and malic acid (MA) on growth performance, antioxidant capacity, haematology and immune response of Carassius auratus gibelio. Carassius auratus gibelio were randomly divided into six groups, with three replicates in each group and 20 fish in each replicate.The six groups were fed a basic diet with organic acid supplementation (control group, 0.2%MA, 0.2%MA + 0.1%CA, 0.2%MA + 0.2%CA, 0.2%MA + 0.4%CA and 0.2%MA + 0.6%CA) for 8 weeks respectively. The results showed that compared with the control group, the weight gain rate and specific growth rate significantly increased in organic acid-fed groups (p < .05). The highest value was in the 0.2%MA + 0.2%CA group. However, there were no significant differences in survival rate, red blood cells or white blood cells between groups. The contents of ALT, AST and LDH in Carassius auratus gibelio fed with organic acids increased, especially in 0.2%MA + 0.4%CA and 0.2%MA + 0.6%CA groups. However, there was no significant difference between the 0.2%MA + 0.2%CA group and the control group. In addition, the highest values of GSH and T-AOC were found in the 0.2%MA + 0.6%CA group. Compared with the control group, there were no significant differences in the expression of HSP70 or LZM (p > .05), but the expression of Il-1β, IL-10 and TNF-α was up-regulated in the 0.2%MA + 0.4%CA and 0.2%MA + 0.6%CA groups. The results showed that the growth performance, antioxidant capacity, haematological parameters and expression of immune-related genes were significantly improved by adding organic acids to the feed of Carassius auratus gibelio. However, excessive addition of organic acids may cause liver injury, and the optimal addition amount in this experiment was 0.2%MA + 0.2%CA. K E Y W O R D S antioxidant capacity, citric acid, growth performance, haematological parameters, immune response, malic acid| 2767 ZHANG et Al. Ash 7.12% 7.12% 7.12% 7.12% 7.12% 7.12%