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
Pelecus cultratus Pelecus cultratus Pelecus cultratus, known variously as the sichel, the ziege, the sabre carp or sabrefish, is a species of cyprinid fish from an Eastern Europe and adjacent Asian regions. It is the only species of its genus. This species inhabits lower reaches of rivers and brackish waters of eastern Baltic, Black, Caspian and Aral Sea basins. This fish has no major threats and the IUCN lists it as being of "Least Concern". The ziege resembles a large Baltic herring in appearance. It grows to about in length. It has a keel on its belly which from the side looks