In this study, effects on fatty acid composition of D. magna produced in the different nutritional mediums (S. acuminatus, yeast, S. acuminatus+yeast, fish oil and yeast+fish oil) were investigated. Considerable differences were found in fatty acid composition of D. magna fed with algae, yeast and fish oil. D. magna fed with algae contains considerable amounts of PUFA (46.2%), though this algae is completely bare of EPA acids. D. magna fed with yeast was contained highest of MUFA (53.5%). In contrast to algae, yeast contains mainly 16:1 and 18:1 acids and was devoid of 18:3 or PUFA. D. magna fed with fish oil contained considerable amounts of PUFA especially, EPA and DHA acids. The rate of synthesis of these acids is rather low, although fish oil contains considerable amounts of these fatty acids.