Separation of EPA and DHA was studied using zeolite 13X molecular sieves modified with methylamine, ethylamine, propylamine, butylamine, and silver nitrate, respectively. The temperature exerted different effects on the adsorptions of EPA and DHA by the various modified 13Xs. The optimal adsorption temperature was 40 ℃ for the 13X samples modified with propylamine, butylamine, and silver nitrate, whereas those modified with methylamine and ethylamine displayed adsorption amounts that continued to increase, even above 45 ℃. Desorption was studied using hexane as solvent containing ethanol and CO2 as the supercritical fluid. Hexane containing 0.5 % ethanol under sonication showed 26.8 and 25.4 % recoveries of EPA and DHA, respectively, in the case of 13X modified with methylamine. Supercritical CO2 fluid displayed superior selectivity and high recoveries for the desorption of DHA and EPA from the 13X modified with butylamine. In this case, the maximum desorption of DHA was 8.42 mg (97.6 % recovery) at a CO2 density of 0.45 g/mL at 45 ℃, whereas the EPA desorption was only 1.26 mg (10.7 % recovery). The desorption amount and recovery of DHA were 6.7 and 9.1 times those of EPA, respectively.