Fish, undammed You wouldn’t be a freshwater fish for quids in this world. As human culture and ingenuity has progressed, the construction of instream barriers such as dams and weirs has grown as a significant threat to freshwater fish species worldwide. There are more than 2 million dams and other stream barriers in the US alone. Now, a team of researchers from the University of New South Wales (UNSW) has found a way to get fish around – or rather over – barriers, reconnecting them with breeding grounds and preferred habitats. They’ve developed a “fishway” that utilises the acceleration of flows in a tube system to pump the fish – protected by a cushion of water – vertically through a tube up and over an obstruction, thus delivering them safely into the water on the other side.