Marine fish and pelagic fish have contain of fatty acids. Fat or fish oil can be used as the source of fatty acid for human body if that component has been separated from other substances such as water or extracted from fish flesh. Pelagic fish such as Indonesia Mackerel has the potential of high fatty acid content. Fatty acids contained in fish oil are classified as unsaturated fatty acids (omega-3). Fish oil stability is very low so it need to storage at low temperatures. The aims of this study was to determine the omega-3 fatty acids in Indonesia Mackerel Fish oil during storage at low temperatures. The method of extracting fish oil used is wet rendering. Materials used in this research was Indonesian Mackerel (Restrelliger sp). This research was experimental laboratoris with three repetitions. Analysis of the parameters observed during storage of fish oil are fatty acid profiles, yields, peroxide value, and organoleptic value such as color and aroma. The results showed a decrease in the amount of Omega-3 fatty acids content during storage by 6,382% relative, peroxide value increased by 1,86 meq/kg, Organoleptic value of color and aroma decreased by 0,01 and 0,09. The yield of fish oil is 0,62%. fatty acids. Fat or fish oil can be used as the source of fatty acid for human body if that component has been separated from other substances such as water or extracted from fish flesh. Pelagic fish such as Indonesia Mackerel has the potential of high fatty acid content. Fatty acids contained in fish oil are classified as unsaturated fatty acids (omega-3). Fish oil stability is very low so it need to storage at low temperatures. The aims of this study was to determine the omega-3 fatty acids in Indonesia Mackerel Fish oil during storage at low temperatures. The method of extracting fish oil used is wet rendering. Materials used in this research was Indonesian Mackerel (Restrelliger sp). This research was experimental laboratoris with three repetitions. Analysis of the parameters observed during storage of fish oil are fatty acid profiles, yields, peroxide value, and organoleptic value such as color and aroma. The results showed a decrease in the amount of Omega-3 fatty acids content during storage by 6,382% relative, peroxide value increased by 1,86 meq/kg, Organoleptic value of color and aroma decreased by 0,01 and 0,09. The yield of fish oil is 0,62%.