@Ashwin_s (and @Chris_Falter):
In fact, with variants as different as the blind fish in the cave and the sighted-fish (belonging to the same species), the question of “common ancestry” is not mute at all. In fact, it proves that “common ancestry” has much more explanatory power than simply saying “God specially creates most life forms”!
Do you think God would intentionally use Special Creation to a species that was both sighted and non-sighted (even without eyes?)?
Or does that seem much more like something that God would arrange through common descent, using Natural Selection to help execute his plans for that fish?