HomeFish encyclopediaRay-finned fishesFlatfishesAmerican solesPlainfin sole Plainfin sole (Achirus declivis) Scientific name: Achirus declivis Chabanaud, 1940 The Plainfin sole (Achirus declivis) is a brackish-water fish of the family Achiridae. Native range: Western Atlantic, Belize to Santa Catarina, Brazil; also Trinidad, Jamaica, St. Barth?lemy, and Suriname. BiologyDorsal spines (total): 0; Dorsal soft rays (total): 55-60; Anal spines: 0; Anal soft rays: 43 - 46Source: FishBase, licensed CC BY-NC 4.0. Species factsScientific nameAchirus declivisFamilyAchiridae (American soles)OrderPleuronectiformes (Flatfishes)ClassActinopterygii (Ray-finned fishes)Maximum length18.0EnvironmentMarine; brackish; demersalClimateTropicalDistributionWestern Atlantic: Belize to Santa Catarina, Brazil; also Trinidad, Jamaica, St. Barth?lemy, and Suriname.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