Fish Counter Window
These specialty viewing windows are underwater windows that allow the viewer to be able to see fish at hatcheries, rivers etc. The two underwater windows were designed to fit into the fish ladder in Iffezheim. Here in the upper Rhine valley the water is dammed by several barrages. The ladders enable the fish to migrate back to their hatching grounds bypassing the dams. As the current in these bypasses is high, a constant observation of the underwater flow is necessary to check if the fish can actually make it up the ladder.
The Hydrosight windows replace existing glasses, which were not performing well. Because of the current and the risk off scratches, Hydrosight used laminated safety glass. Fish ladders in rivers are one of the few exceptions, were Hydrosight recommends safety glazing. Standard underwater windows make use of acrylic.