Fish is by far a high source of proteins and fats, regarding the species. Therefore, the presented work tries to identify, through the processed mackerel, the fatty acids known to have a high nutritious value. Firstly, it has been studied by the literature, the influence of the technological treatment on the chemical composition of a fish. Particularly, the impact of the fermentation on the lipids of the fat fish. Fermented fish (lanhouin), has been produced using the improved technology of fermented fish process. The fermented fish (lanhouin) was obtained through the fermentation of marine fish such as mackerel, fished in the gulf of Benin. Several studies have dealt with fatty acids from marine species; but referring to bibliographical notes, there are less deep studies on the presence of fatty acids found in fermented fish. Secondly, the fat has been extracted using three different methods such as Touchstone