Disinfection efficacy of chlorine and peracetic acid on both wash water and Pangasius hypophthalmus fillets was determined. First, the decontamination efficacy of the washing step with chlorinated water applied by a Vietnamese processing company during trimming of Pangasius fillets was evaluated and used as the basis for the experimental set-up of the laboratory scale. As chlorine was only added at the beginning of the batch and used continuously without renewal for 239 minutes; a rapid increase of the bacterial counts and a fast decrease of chlorine in wash water were found. This could be explained by the rapid accumulation of organic matter (ca. 400 mg O2/L of COD after only 24 minutes). Second, for the lab scale experiments, a single batch approach (one batch of wash water for treating a fillet) was used. Chlorine and PAA were evaluated at 10, 20, 50 and 150 ppm at contact times of 10, 20 and 240s. Washing with chlorine and PAA wash water resulted in a reduction of E. coli on Pangasius fish which ranged from 0-1.0 and 0.4-1.4 log CFU/g, respectively while less to no reduction of total psychrotrophic counts, lactic acid bacteria and coliforms on Pangasius fish was observed. However, in comparison to PAA, chlorine was lost rapidly. As an example, 53-83% of chlorine and 15-17% of PAA were lost after washing for 40s (COD = 238.2 ± 66.3 mg O2/L). Peracetic acid can therefore be an alternative sanitizer. However, its higher cost will have to be taken into consideration. Where (cheaper) chlorine is used, the processors have to pay close attention to the residual chlorine level, pH and COD level during treatment for optimal efficacy.