Application of the circular economy to fish scale waste

Fish is a prominent protein source due to its affordability and nutritional safety. Although many people consume fish, they might not know how much fish scale debris is produced by the food and aquaculture sectors. The fish processing industry has grown significantly and contributes to global economic growth. Million tons of fish waste end up in landfills worldwide yearly. Fish scale disposal in landfills has the potential to seriously pollute the ecosystem. Hence, fish-scale waste can create valuable products with favorable environmental and financial effects. Fish scales are a naturally occurring resource with abundant applications as biomaterials. They are composed of collagen, hydroxyapatite, chitin, and gelatin, and their hierarchical structure is similar to that of human hard tissues. It is advantageous for fish scales due to its mechanical attributes, biodegradability, and biocompatibility. This paper reviews the latest importance of fish biomass/industry waste products in extracting biomaterials or converting them into value-added products. A summary of the most significant applications of fish scales over the previous three years in diverse fields such as food science and engineering, adsorbent, agriculture, tissue engineering, cosmetics, pharmaceutical and nutraceuticals, etc. The review also discusses the need for and importance of circular economy concepts related to fish scale biomass conversion and its future perspectives. There is enormous potential in the conversion of fish scale biomass, which is predicted in the future with the expansion of technological advancements.