Exodus 7:18

The fish that is in the river shall die. — The natural discoloration of the Nile, whether by red earth or by Cryptogams and Infusoriæ, has no pernicious effect at all upon the fish, nor is the water rendered by these discolorations at all unfit for use. The Nile naturally abounds with fish of various kinds; and though to Europeans they have, most of them, an insipid taste, yet, both in ancient and in modern times, the subsistence of the natives has been largely drawn from this source. It was a severe punishment to the Egyptians to be deprived of their fish supply. It was also implied contempt in regard of their religious worship, since at least three species of the Nile fish were sacred — the oxyrhineus, the lepidotus, and the phagrus, or eel. (Herod. ii. 72; Plut. De Ibid. et Osir. vii. 18, 22.)

The river shall stink. — The Nile is said to have sometimes an offensive odour naturally; but the phenomenon is not marked, and can scarcely be that which is here alluded to, when the blood-like waters, laden with the bodies of putrid fish, caused a disgust and horror that were unspeakable.