Fish species refer to the various types of fish that exist in aquatic environments, including oceans, rivers, and lakes. Each species has unique characteristics, such as size, color, and habitat preferences. Some common examples of fish species include salmon, trout, and tuna. Fish species are classified into different groups based on their biological traits. These groups include bony fish, cartilaginous fish, and jawless fish. Understanding fish species is important for conservation efforts and maintaining healthy ecosystems, as each species plays a specific role in its environment.