Exodus:7:17-18
kjv@Exodus:7:17 @ Thus saith the LORD, In this thou shalt know that I am the LORD: behold, I will smite with the rod that is in mine hand upon the waters which are in the river, and they shall be turned to blood.
kjv@Exodus:7:18 @ And the fish that is in the river shall die, and the river shall stink; and the Egyptians shall lothe to drink of the water of the river.