HomeFish encyclopediaRay-finned fishesFlatfishesLarge-tooth floundersSmallmouth flounder Smallmouth flounder (Etropus microstomus) Scientific name: Etropus microstomus Gill, 1864 The Smallmouth flounder (Etropus microstomus) is a marine fish of the family Paralichthyidae. Native range: Western Atlantic, Canada to North Carolina to Mississippi, USA, including the northern Gulf of Mexico. BiologyDorsal soft rays (total): 68-83; Anal soft rays: 53 - 62Source: FishBase, licensed CC BY-NC 4.0. Species factsScientific nameEtropus microstomusFamilyParalichthyidae (Large-tooth flounders)OrderPleuronectiformes (Flatfishes)ClassActinopterygii (Ray-finned fishes)Maximum length13.0Depth range91 m (299 ft)EnvironmentMarine; demersal; oceanodromous; depth range ? - 91 mClimateSubtropicalDistributionWestern Atlantic: Canada to North Carolina to Mississippi, USA, including the northern Gulf of Mexico.Conservation status (IUCN)Not EvaluatedThreat to humansHarmlessResilienceHigh, minimum population doubling time less than 15 months (Preliminary K or Fecundity.) SourcesTaxonomy, distribution and biology data: FishBase (Froese, R. and D. Pauly, eds.), licensed CC BY-NC 4.0.Last updated 27 September 2026