Algae (microalgae) are plant-like microorganisms that live in both salt and freshwater environments. Certain types of marine algae are primary sources of the Omega-3 fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), and it is by consuming algae in their diet that fish obtain Omega-3s. Algal Oil is extracted from microalgae and purified to provide some foods and supplements with plant-based sources of Omega-3 fatty acids.