Exodus 7:20 - Clarke's commentary and critical notes on the Bible

And Moses and Aaron did so, as the LORD commanded; and he lifted up the rod, and smote 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. All the waters - were turned to blood - Not merely in appearance, but in reality; for these changed waters became corrupt and insalubrious, so that even the fish that were in the river died; and the smell became highly offensive, so that the waters could not be drank; Exodus 7:21.