The most important raw materials used in the fish feed industry are fishmeal and fish oil. Fishmeal is the preferred as a protein source due to its high protein content, good amino acid balance, lack of antinutrients and high palatability. However, because of its cost and limited resources, its substitution is a basic prerequisite for the sustainability of aquaculture. The number of feedstuffs with high protein content that can currently be used to replace fishmeals is very limited. They include plant feedstuffs, like soybean meal and corn gluten meal, and animal by-products, like poultry by-products. All these materials have deficiencies in essential amino acids. The use of plant materials is furthermore limited since they contain growth inhibitors. The optimization of technological treatments to remove anti-nutrients in plant materials could increase their use in fish feeds and may reduce reliance on fish products.