A caudal fin is the tail fin of a fish, located at the rear end of its body. It plays a crucial role in propulsion, helping the fish to swim forward and change direction. The shape and size of the caudal fin can vary significantly among different species, influencing their swimming style and speed. In addition to aiding movement, the caudal fin can also serve as a means of communication and display. For example, some fish, like betta fish, have elaborate caudal fins that are used during mating rituals or to establish territory. The design of the caudal fin is essential for the fish's overall adaptability in its environment.