What is composition of fish scales?

Fish scales are primarily composed of collagen, a protein that provides strength and flexibility. They also contain minerals such as calcium carbonate or hydroxyapatite, which contribute to their hardness and protective function. The outer layer of scales is often covered by a thin layer of enamel-like substance called ganoine in certain species, adding to their durability. Additionally, scales can vary in structure and composition depending on the species of fish.