What an exciting time , the OzFish Onk Habitat group have been making great headway in the restoration of habitat in the Onkaparinga river . We have finished stage one which was to deploy Limestone blocks into the Onk to place some substrate for small critters to attach to and hide around . These living critters such as oysters , barnacles and small crustaceans will in turn encourage bigger critters to congregate in the area . The placement of these blocks also should help the tides that flow over them to scour more of the sediment from the bottom of the river in an aid to make a deeper hole i