purposes.

Exodus 7:19
And the LORD said to Moses, "Tell Aaron, 'Take your staff and stretch out your hand over the waters of Egypt--over their rivers and canals and ponds and reservoirs--that they may become blood.' There will be blood throughout the land of Egypt, even in the vessels of wood and stone."

Exodus 8:5
And the LORD said to Moses, "Tell Aaron, 'Stretch out your hand with your staff over the rivers and canals and ponds, and cause the frogs to come up onto the land of Egypt.'"

Deuteronomy 11:10
For the land you are entering to possess is not like the land of Egypt, from which you have come, where you sowed your seed and irrigated on foot, like a vegetable garden.

for fish.