Fish Scales: A Multifunctional Biomaterial from Nature

Fish scales, as products of long‐term natural evolution, are biomaterials featuring an intricate integration of inorganic and organic components, exhibiting species‐specific multilayered micro‐nano structures. Owing to its gradient mineralization, the scale shows a progressive decrease in hardness from the outer to the inner layer, which facilitates a continuous shift from rigidity to flexibility. This hierarchical structure provides important inspiration for the development of novel flexible biomimetic protective materials. Beyond structural design inspiration, the primary components of fish scales (e.g., hydroxyapatite, collagen) possess excellent biocompatibility and multifunctionality, endowing them with broad prospects across diverse fields including biomedicine, environmental remediation, energy storage, cosmetics, food, and agriculture. However, transforming this potential into practical use faces significant challenges. These arise from the technical contradiction of extracting key components efficiently while preserving their bioactivity, coupled with the industrial bottleneck of achieving both precise biomimetic reconstruction of their natural nanocomposite structure and scalable manufacturing. This review comprehensively summarizes recent advances in fish scales research, with a focus on their role as biomimetic models and functional applications, and critically discusses the challenges and future opportunities toward industrialization.