The byproducts generated during fish processing can represent up to 70% of the raw material entering the industry, and some of these byproducts are rich in high-quality proteins and other nutrients that could be used for human consumption. The products derived from these byproducts can be considered high-value-added products or coproducts, with the potential to create new ingredients and innovative food products. Among these, Fish protein concentrate (FPC) can be used as an ingredient in formulations for protein enrichment by food industry. Notably, the absence of global standardization in industrial processes for FPC production stems from the limited number of countries with established regulations and the scarcity of industries offering specialized equipment for industrial production. This dearth inhibits uniformity and efficiency in FPC manufacturing worldwide. These factors make FPC production inefficient and the quality of the final product unsatisfactory, mainly because of the presence of a large amount of lipids, which can be a concern and necessitate the use of chemical and physical lipid removal methods. In this critical review, information about FPC was compiled, with an emphasis on the byproduct of fish processing, processing techniques, and the nutritional and techno-functional aspects of this coproduct and formulated foods.