The West African pygmy herring (Sierrathrissa leonensis) is a very small fish, reaching a maximum length of 3 cms SL, is a member of the herring family Clupeidae, and belongs to a radiation of the subfamily Pellonulinae in the freshwater systems of western and central Africa that includes such species as the Microthrissa royauxi of the Congo River basin and Limnothrissa miodon of Lake Tanganyika.