Fish scales are small, flat structures that cover the skin of most fish. They serve as a protective barrier against parasites and environmental hazards. Scales can vary in size, shape, and texture depending on the species of fish, and they are made primarily of a protein called collagen. There are different types of fish scales, including cycloid, ctenoid, and ganoid scales, each with unique characteristics. Scales also play a role in hydrodynamics, helping fish move efficiently through water. Additionally, they can reflect light, contributing to the fish's coloration and camouflage in their aquatic habitats.