Post-harvest handling / processing of fishery commodities requires large amounts of water and energy to overcome their perishable properties. Water is needed as raw/auxiliary material and to ensure that the production process and its environment meet the sanitary and hygiene principles. Meanwhile, large amount of energy is required for the transportation of raw materials and products, cold chain system during the process and operations of processing machines. They contribute towards the environmental impact of fish processing. This study used life cycle assessment to estimate the potential environmental impact of small scale mackerel fish processing. The results showed that the fish processing has contributed to 0.079 kg SO 2 eq acidification potential, 9.66 kg CO 2 eq climate chang-GWP 100, 0.02 kg PO 4 eq Eutrophication-generic, 0.17 kg 1.4 DCB eq human toxicity-HTP inf, and 0.0015 kg ethylene eq photochemical oxidation-high NO x. Wastewater treatment implementation simulation showed elimination of direct emissions that contribute to eutrophication and increasing the potential of other process associated with energy consumption.