Wesley Malcorps explains how a large proportion of the fish farmed in Europe is discarded, sometimes up to 50% of the whole fish. However, this is dependent on the consumption habits, generally speaking, the north of Europe prefers fillets, while the south of Europe prefers the purchase of whole or gutted fish. This has an impact on the availability of by-products at the processing stage. Reducing waste reduces environmental impacts in a number of ways but sustainability analyses of aquaculture has typically ignored the fate and value of processing by-products. Because of the nutrient content, fish by-products have applications in human food, livestock and pet food. However, there are also some barriers to overcome, including consumer acceptance of different product forms.