For a short period of time (24 h), whether juvenile crayfish or subadult crayfish are exposed to a low dissolved oxygen environment, P. clarkii will always be in a state of stress, thus inducing the organism to increase the activities of SOD and CAT antioxidant enzymes and gene expression levels and improve the immune capacity of the organism to combat the oxidative damage caused by stress and infection by pathogenic bacteria. Here, CAT is linked to infection.