Fish is an inexpensive source of high-quality protein as well as valuable micronutrients. Increasing the volume of fish and producing more fish feed is necessary to ensure the necessary consumption. One of the main components of fish feed is oil, the most crucial lipid source in fish feed. Fish oil is easily digestible and contains essential fatty acids, but replacing fish oil with alternative oil might make the fish feed more sustainable. Vegetable oils can replace fish oil due to reduced costs due to continued growth in production volumes, high availability and better economic value. Soy, linseed, rapeseed, sunflower, palm and olive oils are often used in fish feed. Also, microalgae oil is rich in essential fatty acids and a long-lasting alternative to fish oil. Important is not only the environmental impact of oil alternatives but also how these alternatives maintain or even improve the overall composition and quality of fish feed and products. An LCA assessment was performed to determine the environmental impact of microalgae, rapeseed oil, and fish oil. Where LCA system boundaries are “cradle to gate” and a functional unit of 1 kg of oil. LCA inventory is data from a literature review and SimaPro Ecoinvent database. The results obtained from LCA are based on PEFCR impact assessment categories. The LCA results show that the single score value for microalgae oil is 1.00E+00 mPt, for rapeseed oil 3.55E-01 mPt and fish oil 1.61E-01 mPt. It should be noted that the comparison presented reflects a generic comparison of alternatives, as the input data is derived from the literature analysis and the Ecoinvent v3.8 database.