Ameliorative effects of pyrroloquinoline quinone on oxidized fish oil-induced growth retardation, immune suppression, and oxidative stress in yellow catfish Tachysurus fulvidraco

Fish oil is the primary oil source in aquafeeds, but is susceptible to oxidation during production and storage, thereby leading to oxidative stress in fish. Pyrroloquinoline quinone (PQQ) is a novel redox cofactor that possesses numerous pharmacological properties. Hence, the aim of this study was to evaluate whether dietary PQQ supplementation could alleviate stress response of yellow catfish ( Tachysurus fulvidraco ) caused by oxidized fish oil. Fish were fed four experimental diets containing fresh and oxidized fish oil either with or without PQQ (0 or 5 mg kg −1 ) supplementation for 8 weeks. Results revealed that dietary oxidized fish oil significantly decreased growth performance of fish, fat content in whole-body, and the immunological parameters. Also, it significantly elevated aspartate aminotransferase and alanine aminotransferase activities, as well as the levels of total cholesterol, triglyceride, and glucose in serum. Meanwhile, oxidized fish oil decreased antioxidant enzyme activities (superoxide dismutase and glutathione peroxidase) and total antioxidant capacity but increased MDA level in serum. However, the addition of PQQ in the oxidized fish oil diet could overcome the negative impacts of oxidized fish oil on yellow catfish and normalise the detected parameters nearly to the control values. Taken together, long-term feeding of oxidized fish oil diet destroyed liver, disordered lipid metabolism, diminished nonspecific immunity as well as caused oxidative stress, and eventually resulted in growth retardation of yellow catfish, whereas dietary PQQ supplementation had a significant ameliorative role in adverse effects induced by dietary oxidized fish oil, and therefore, may be recommended for use in aquaculture to prevent oxidized lipid. • Oxidized fish oil decreased growth performance of yellow catfish. • Oxidized fish oil destroyed liver and disordered lipid metabolism of yellow catfish. • Oxidized fish oil reduced nonspecific immunity and induced oxidative stress of yellow catfish. • Pyrroloquinoline quinone alleviated the negative effects of oxidized fish oil on yellow catfish.