Serian Borneo sucker

About

Found only in the fast-flowing rocky streams of the Sadong basin in Sarawak, Malaysia, Gastromyzon scitulus is a small hillstream loach that rarely exceeds an inch and three-quarters. Its body is jet black and covered in numerous small, evenly-spaced cream spots, with the head showing a similar pattern and the tail fin carrying iridescent blue streaks in living fish. Like all gastromyzontids, it is built for life in rushing water. The paired fins are held horizontally, the underside is flattened, and the pelvic fins are fused into a suction pad that lets it grip slick rock surfaces with impressive tenacity. Rather than swimming freely, it crawls and shuffles across substrate in the characteristic fashion of the group. Despite being tagged as aggressive and territorial in some records, the reality is more nuanced: individuals may defend favored feeding spots from one another, but the species is generally peaceful toward dissimilar tankmates. Keeping a group of four or more actually softens this territorial edge and brings out more natural social behavior. Suitable companions include small stream-dwelling cyprinids, rheophilic gobies, and similarly-sized loaches, though any larger or more boisterous fish should be avoided. This species is one of the more regularly traded Gastromyzon, though it often arrives unlabeled or mislabeled in mixed shipments, so correct identification at purchase is worth the extra effort.