The video showcases a Betta fish, also known as Siamese fighting fish, swimming in a tank. The fish has a dark blue body with a mix of black and white on its fins and tail. The Betta fish is seen gracefully moving around the tank, with its fins and tail flowing elegantly. The background consists of green aquatic plants, providing a natural habitat for the fish. The lighting in the tank highlights the vibrant colors of the fish and the plants.