The total fatty acids of Nannochloropsis oculata grown under optimum growth conditions and different salinity grades ranged from 25%_o, to 45%_o during both exponential and stationary growth phases were analysed using Gas liquid chromatography (GIC). During the exponential growth phase, the domenant fatty acids were monounsaturated chains, while during the stationary growth phase, the acids were saturated, monounsaturated and polyunsaturated long chains. The optimum salinity for the production of the essential polyunsaturated C₁₈ andC₂₀ components forthe fish larvae was 45%_o during the stationary growth phase.