Date Time New fishway technology to get fish up and over those dam walls The tube fishway allows fish to glide past dam walls, weirs and other river barriers, with the potential to revitalise Australia’s ailing freshwater fish stocks. A view of Manly Dam at Sydney’s Northern Beaches. Photo: UNSW Engineers and scientists at UNSW Sydney have come up with an ingenious way to get fish past dam walls, weirs and other barriers blocking their migration in Australian rivers. The so-called tube fishway is a low-cost and low-energy installation that works by pumping fish at high velocity – protected by a cushion of water – through a tube running over the obstructing barrier to deliver them safely into the water on the other side.