Dietary Supplement. The Bigger Picture of Fish Oils. DHA. EPA. No Fishy Aftertaste. Mercury-Free Fish oils contain long-chain fatty acids, including docosahexaenoic acid and eicosapentaenoic acid . DHA and EPA are essential fats that cannot be made by your body. So, consuming them through foods like salmon and supplements such as the ON Fish Oil Softgels that you are holding in your hands is the only way to get DHA and EPA. Our Fish Oil Softgels are mercury-free and enteric-coated, which means that you get all of the benefits of fish oils without the fishy aftertaste that you might encounter without this special.