What is the classification of fish based on habitat and morphology?

Fish can be classified based on habitat into three main categories: freshwater, saltwater (marine), and brackish water species. Morphologically, they can be categorized by body shape, fin structure, and skeletal features, leading to classifications such as bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). Each group exhibits unique adaptations suited to their environments and lifestyles, influencing their feeding strategies, locomotion, and reproductive behaviors.