Exodus 7:19-21

Then the LORD spoke to Moses, “Say to Aaron, ‘Take your rod and stretch out your hand over the waters of Egypt, over their streams, over their rivers, over their ponds, and over all their pools of water, that they may become blood. And there shall be blood throughout all the land of Egypt, both in buckets of wood and pitchers of stone.’ ” And Moses and Aaron did so, just as the LORD commanded. So he lifted up the rod and struck the waters that were in the river, in the sight of Pharaoh and in the sight of his servants. And all the waters that were in the river were turned to blood. The fish that were in the river died, the river stank, and the Egyptians could not drink the water of the river. So there was blood throughout all the land of Egypt.