Cartilage is a crucial component of the vertebrate skeletal system, providing structural integrity, flexibility, and adaptive functions across species. In teleost fish, cartilage exhibits significant morphological and functional diversity, providing specialized biomechanical properties essential for aquatic life. This study presents a detailed histological, immunohistochemical, and ultrastructural investigation of cartilage in molly fish (Poecilia sphenops), identifying five distinct types of cartilage: hyaline-cell, scleral,