HomeFish encyclopediaRay-finned fishesSmeltsPencil smeltsRobust smallmouth Robust smallmouth (Nansenia ardesiaca) Scientific name: Nansenia ardesiaca Jordan & Thompson, 1914 The Robust smallmouth (Nansenia ardesiaca) is a marine fish of the family Microstomatidae. Native range: Indo-West Pacific. BiologyDorsal soft rays (total): 9-10; Anal soft rays: 9 - 10; Vertebrae: 46 - 48. Branchiostegal rays 4.Source: FishBase, licensed CC BY-NC 4.0. Species factsScientific nameNansenia ardesiacaFamilyMicrostomatidae (Pencil smelts)OrderOsmeriformes (Smelts)ClassActinopterygii (Ray-finned fishes)Maximum length20.0Depth range260–553 m (853–1814 ft)EnvironmentMarine; bathydemersal; depth range 260 - 553 mClimateDeep-waterDistributionIndo-West Pacific.Conservation status (IUCN)Not EvaluatedThreat to humansHarmlessUsesFisheries: of no interest SourcesTaxonomy, distribution and biology data: FishBase (Froese, R. and D. Pauly, eds.), licensed CC BY-NC 4.0.Last updated 27 September 2026