Torrent loaches (Gastromyzon sp.). X-ray of a section through two torrent loaches, showing their skeletons. The crescent-shaped paired fins on the underside of torrent loaches work like suction cups to help them hold their position on a rock or streambed in fast-flowing waters. These specimens belong to a newly discovered species that has not yet received a scientific name. They measure 7.5 centimetres in length.