River Tywi these fish to over in weight. In summer and autumn there is also a substantial run of Atlantic salmon ("Salmo salar"). In May the Tywi has a run of the rare and protected twaite shad ("Alosa fallax") and allis shad ("Alosa alosa"). The Tywi also contains brown trout, eels, pike, and a variety of small fish species, and is home to brook lampreys, river lampreys and sea lampreys. The Tywi has the distinction of having accidentally produced by far the biggest fish ever taken on rod and line in fresh water in Britain. This was a sturgeon ("Acipwienser sturio") weighing
Araucanian herring Araucanian herring The Araucanian herring, "Clupea bentincki", is a fish species in the genus "Clupea" of the family Clupeidae. It is an epipelagic fish, silvery below and dark blue above, which schools in coastal waters off the west coast of South America. There it filter feeds on smaller plankton such as diatoms. It reaches sexual maturity when it is about 10 centimetres long, and is a pelagic spawner, spawning between June and November. The Araucanian herring is a commercial species, largely used for fishmeal. Based on the FAO fishery statistics, it was the 12th most important capture fish species in