Curcumin was observed to enhance the activities of antioxidant enzyme SOD, CAT, and GPx by upregulating the expression of Cu/Zn SOD, MnSOD, CAT, and GPx mRNA, which was associated with the Keap1/Nrf2 signaling pathway in grass carp following infection with Aeromonas hydrophila [59]. Here, SOD2 is linked to infection.