Sforno on Exodus 8:6/ספורנו על שמות ח׳:ו׳

1כדברך, in accordance with your wish. You had stipulated that the crocodiles should be removed from yourself, and from your people,” (verse 4) you did not ask for them to be eliminated from nature as a species.

2למען תדע כי אין כה' אלוקנו, that there is no power in the universe other than the G’d of the Israelites who possesses the power to fundamentally effect changes in natural law. At that time, consigning crocodiles exclusively to the river Nile was a fundamental change in the habitat of this species. This species is different from all other known species in that instead of moving its lower jaw when eating, it moves its upper jaw. It also ingests food without excreting waste products. G’d will banish the species only from you and your houses, as this is all you asked for.