As the consumption of fish in the human diet increases, a larger amount of production is needed. The growing demand for fish also has an impact on fish feed, its production efficiency and the sustainability of using raw materials. To evaluate the sustainability of raw materials and the impact on the environment, three protein alternatives are compared - Black Solder Fly, Yellow Mealworm and soybean. Using Life Cycle Assessment (LCA), an environmental impact assessment is performed to define which of the protein alternatives is more sustainable. Results from LCA show that the largest impact is Yellow Mealworm protein, then soybean protein and Black Soldier Fly protein. In Yellow Mealworm protein production, the largest impact (83%) came from larval rearing and the rest from electricity. Soybean protein also has a greater impact on soybean cultivation processes. However, the biggest impact of the Black Soldier Fly protein comes from the electricity consumption, probably from the fact that all the necessary processes take place in different electrical installations. The results show the general picture of the impact of protein alternatives that can be used in fish feed production. The study can be further developed by comparing other fish feed ingredients and their environmental impacts. Also the overall impact of fish feed can also be assessed when protein alternatives are used. Existing alternatives can certainly be improved to reduce the environmental impacts and use RES in production processes and choose more sustainable alternatives to raw materials and efficient waste management.