Alosa "oligorakered." The multirakered are primarily plankton feeders, the oligorakered have large rakers and are predators, and the medium-rakered generally consume a mixed diet. Most current species of the genus "Alosa" in North America can be found in Florida, whereas the distribution of most of them is broader. Morphology is notoriously liable to adapt to changing food availability in these fish. Several taxa seem to have evolved quite recently, making molecular analyses difficult. In addition, hybridization may be a factor in shad phylogeny. Nonetheless, some trends are emerging. The North American species except the American shad "A. sapidissima" can probably be
West African pygmy herring West African pygmy herring The West African pygmy herring ("Sierrathrissa leonensis") is a very small fish, reaching a maximum length of 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. It is the only species of its genus. A very small fish which shows a reduction in size and some neoteny when compared to its larger relatives. The West African pygmy herring is