Osteichthyes, commonly known as bony fish, are a diverse group of fish characterized by their bony skeletons, as opposed to cartilage. This class includes familiar species like salmon, tuna, and goldfish. They are found in various aquatic environments, from oceans to freshwater lakes, and play essential roles in ecosystems and human diets. These fish possess a swim bladder, which helps them maintain buoyancy in water. Osteichthyes are divided into two main groups: ray-finned fish, which have fins supported by bony rays, and lobe-finned fish, which have fleshy, lobed fins. Their adaptability and variety make them a fascinating subject of study in marine biology.