Fish use armour in the form of scales, whether 'cosmoid', 'ganoid' or 'placoid' and in some cases spines, such as on fish such as the stickleback.
Fish possess armor in the form of scales, which can be either 'cosmoid', 'ganoid', or 'placoid'. In some cases, they also have spines, such as those seen on species like the stickleback.