Fish (concept)

Fish are aquatic vertebrates characterized by their gills, fins, and streamlined bodies, enabling them to live and move efficiently in water. They breathe through their gills, absorb oxygen from water, and often have scales covering their skin. Fish vary widely in size, shape, and behavior, occupying diverse freshwater and saltwater habitats. They play essential roles in aquatic ecosystems, serving as predators, prey, and contributors to the health of their environments. As a group, fish are among the most diverse vertebrates, with thousands of species adapted to a broad range of aquatic conditions.