Retail-cut muscle foods are especially susceptible to oxidative degradation and formation of harmful reactive oxygen species (ROS) owing to exposure to oxygen, bright lights and contact with metal counters. Due to extended cooking at temperatures near the pH optima of most of starter culture proteases during its Cheddar cheese manufacture, the resulting whey (CW) is naturally rich in antioxidative peptides and Maillard reaction products. In the present study, we report the antioxidative efficacy of CW when used in an edible coating, with and without chitosan (Ch), to reduce protein and fat degradation in stored farm-raised retail-cut catfish and the accumulation of ROS in the muscle. Fresh catfish fillet of uniform thickness were cut into cubes of unvarying weight (5g) and geometry, and immersed in dispersions of CW (2% w/v), Ch (1%, w/v) or mixture of both (CW+Ch) in 0.2 M McIlvaine’s iso-ionic buffer (pH 7) at 22°C for 2 min. Protein and lipid oxidation [evident from carbonyl contents (CC) and peroxide values (PV)] of the samples were determined after storage at 4°C for nil, 1, 3, 5 and 7 d . Accumulation of ROS at cellular level was studied using a fluorogenic molecular probe (CellROX Deep Red Reagent, Life Technologies). Results showed significantly (P < 0.05) superior efficacy of the coatings in reducing overall oxidative degradation of samples for most of the storage periods compared with control (immersed only in the buffer). The CW+Ch mixture showed dramatic effects in alleviating lipid oxidation and ROS accumulation. It also reduced CC by ~60% compared with control after 3 d of storage, thus indicating a considerable extension in shelf life. The PV was reduced to ~22 and 16% in the samples immersed in CW+Ch and CW, respectively, after 5 d of storage compared with control. The same samples also exhibited 28 and 21% reduction in ROS accumulation relative to control after the same number of days of storage. The results indicated a vivid potential of this combined approach for combating oxidative degradation of foods and prevention of the formation/accumulation of harmful ROS in foods.