(iii) Rohu fish
Cartilaginous fishes fall under the class Chondrichthyes. They are primarily comprised of cartilage. Cartilaginous fish have gills that open to the ocean through slits. Cartilaginous fish may also breathe through spiracles, rather than gills. Spiracles are located on top of the heads of all rays and skates, and some sharks. These openings allow the fish to rest on the ocean floor and draw oxygenated water in through the top of their head, enabling them to breathe without breathing in the sand.