And the LORD spake unto Moses, Say unto Aaron, Stretch forth thine hand with thy rod over the streams, over the rivers, and over the ponds, and cause frogs to come up upon the land of Egypt. Stretch forth thine hand - over the streams, over the rivers - The streams and rivers here may refer to the grand divisions of the Nile in the Lower Egypt, which were at least seven, and to the canals by which these were connected; as there were no other streams, etc., but what proceeded from this great river.
Related Commentaries of Exodus 8:5
Exodus 8:5
5 And the LORD spake unto Moses, Say unto Aaron, Stretch forth thine hand with thy rod over the streams, over the rivers, and over the ponds, and cause frogs to come up upon the land of Egypt.