Spotted Hillstream Loach

About

Found only in the Se Kong drainage of Laos and Vietnam, Sewellia speciosa is a small gastromyzontid loach built for life in fast-moving, rocky rivers. Its body is flattened top-to-bottom, with horizontally oriented paired fins and a remarkable adhesive disc formed by the ventral surface. An arrangement that lets it grip smooth boulders against powerful currents. The spotted patterning distinguishes it readily from its closest relative, which is striped rather than spotted. In the aquarium, this species needs good water movement, a rocky or gravelly bottom, and plenty of surfaces covered in biofilm and algae to graze on. Despite being listed as beginner-friendly in terms of basic care, its temperament deserves respect: Sewellia speciosa is among the more assertive hillstream loaches and will dominate bottom-dwelling tankmates of similar shape. It does best in groups of six or more, where territorial skirmishes, including the memorable belly-to-belly upright standoff, are distributed across the group rather than focused on a single target. Suitable companions include small mid-water cyprinids and rheophilic gobies rather than other benthic grazers. For breeders, this genus is notably accessible, with spawning sometimes occurring without much intervention, making it a genuinely rewarding project for anyone keeping a well-maintained hillstream setup.