1,3-dibromo-5,5-dimethylhydantoin (DBDMH) is a broad-spectrum and efficient disinfectant used in aquaculture. The present study aimed to know if the response of antioxidative defense system was reversible under different concentrations of DBDMH exposure. The fish were exposed to subacute concentrations of 0.06, 0.3, and 1.5 mg/L for 16 days and then transferred to DBDMH-free water for 10 days. Results showed that SOD/CAT (except 0.06), GPx (only 1.5), GR (only 0.3), T-GSH (only 1.5), and content GSH/GSSG ratio (0.06, 1.5) significantly increased at 1 day after exposure. SOD, CAT, GPx, GR, and T-GSH were decreased in all the groups at 2 days. The recovery results showed that SOD (0.3), GST (all groups), T-GSH contents (1.5), and GSH/GSSG ratios (1.5) were significantly increased, and it suggested the damage produced by 0.06~1.5 mg/L DBDMH were irreversible. The current study suggests such antioxidant responses could be used as the ecological biomarkers for monitoring residual DBDMH in aquatic environments of tilapia ponds, which also provides an early warning of DBDMH for wild fish because of the persistent existence in the contaminated water.