Exodus 7:20-21

20 Moses and Aaron did just as the Lord commanded. In the sight of Pharaoh and of his officials he lifted up the staff and struck the water in the river, and all the water in the river was turned into blood,
21 and the fish in the river died. The river stank so that the Egyptians could not drink its water, and there was blood throughout the whole land of Egypt.
New Revised Standard Version Bible, copyright 1989, Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved.