Oxidized fish oil, as a harmful ingredient in feed, has a negative impact on aquatic animals. But the effect of oxidized fish oil on hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatus), especially the intestinal flora, is not yet understood. In the current study, a 65-day raising experiment with diets containing 0 g/kg, 30 g/kg, 60 g/kg, and 90 g/kg oxidized fish oil was performed (called as R, L, M and H group respectively) to investigate the effects of oxidized fish oil on growth performance, whole body composition, serum biochemical index, intestinal digestive enzyme activities and microbiome composition in juvenile hybrid grouper. Oxidized fish oil inhibited growth performance of pearl gentian grouper. The Moisture, crude protein, and ash content in whole body increased as increasing dietary oxidized fish oil content. The vitamin E content and antioxidant enzyme activity in serum including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) were significantly increased as the oxidized fish oil in the diet increased, but malondialdehyde (MDA) content in serum was significantly decreased. Meanwhile, the D-Lactate (D-LA) and interleukin-10 (IL-10) content in serum was promoted by oxidized fish oil, but interleukin-6 (IL-6) content was suppressed. Moreover, the intestinal digestive enzyme activities were promoted by oxidized fish oil. The oxidized fish oil reduced alpha diversity of intestinal bacteria. At the same time, oxidized fish oil changed the structure of grouper intestinal flora according to beta diversity and line discriminant analysis (LDA) effect size. In conclusion, oxidized fish oil inhibited growth performance, changed the composition of the body and caused oxidative stress and inflammation in the body, but it promoted the secretion of digestive enzymes in the intestine. More importantly, oxidized fish oil reduced the diversity of intestinal flora and changed the structure of intestinal flora.

氧化鱼油作为饲料中的有害成分，对水生动物有负面影响。但氧化鱼油对杂交石斑鱼（♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatus ）的影响)，尤其是肠道菌群，尚不清楚。在本研究中，进行了为期 65 天的饲养试验，日粮中含有 0 g/kg、30 g/kg、60 g/kg 和 90 g/kg 氧化鱼油（称为 R、L、M 和 H 组）分别）研究氧化鱼油对杂交石斑鱼幼鱼生长性能、全身组成、血清生化指标、肠道消化酶活性和微生物组组成的影响。氧化鱼油抑制珍珠龙胆石斑的生长性能。全身水分、粗蛋白和灰分含量随着日粮氧化鱼油含量的增加而增加。血清中的维生素 E 含量和抗氧化酶活性包括超氧化物歧化酶 (SOD)、过氧化氢酶 (CAT)、随着日粮中氧化鱼油含量的增加，谷胱甘肽过氧化物酶（GSH-Px）显着升高，而血清中丙二醛（MDA）含量显着降低。同时，D-乳酸（D-LA) 和白细胞介素 10 (IL-10) 的含量被氧化鱼油提高，但白细胞介素 6 (IL-6) 的含量受到抑制。此外，氧化鱼油促进了肠道消化酶的活性。氧化的鱼油降低了肠道细菌的α多样性。同时，氧化鱼油根据β多样性和线性判别分析（LDA）效应大小改变了石斑鱼肠道菌群的结构。综上所述，氧化鱼油抑制生长性能，改变机体成分，引起机体氧化应激和炎症，但促进肠道消化酶的分泌。更重要的是，氧化鱼油降低了肠道菌群的多样性，改变了肠道菌群的结构。