The European Perch carries a virus known as EHNV, which attacks the native Macquarie Perch. Siltation of the river resulting from erosion of soil also harms native fish. If land managers can meet the challenge of improving their land use, by planting river reeds and trees near waterways, then soil will not be washed into the rivers at such high rates. Native fish species have suffered due to changes in the water supply caused by dams, weirs and irrigation. There has been experimental flooding in some areas to help native fish spawn.
Weirs disrupt the paths used by native fish species.
Native fish need to move long distances to spawn. The Murray-Darling Basin Commission is installing fish ladders to help native fish move past weirs. Some weirs are removed during times of known fish migration. Major storage dams sometimes give out too little water for suitable fish habitats. Flows of water are increased to benefit native fish.