Exodus 7:18

New English Translation

¹⁸Fish^[a] in the Nile will die, the Nile will stink, and the Egyptians will be unable^[b] to drink water from the Nile.”’”

Exodus 7:18 tn The definite article here has the generic use, indicating the class—“fish” (R. J. Williams, Hebrew Syntax, 19, §92).
Exodus 7:18 tn The verb לָאָה (laʾah), here in the Niphal perfect with a vav consecutive, means “be weary, impatient.” The Niphal meaning is “make oneself weary” in doing something, or “weary (strenuously exert) oneself.” It seems always to indicate exhausted patience (see BDB 521 s.v.). The term seems to imply that the Egyptians were not able to drink the red, contaminated water, and so would expend all their energy looking for water to drink—in frustration of course.

New English Translation (NET)