Exodus 7:20-21
7:20 Moses and Aaron did so, just as the Lord had commanded. Moses raised the staff and struck the water that was in the Nile right before the eyes of Pharaoh and his servants, and all the water that was in the Nile was turned to blood.
7:21 When the fish that were in the Nile died, the Nile began to stink, so that the Egyptians could not drink water from the Nile. There was blood everywhere in the land of Egypt!