Natural selection will not favor fish with fingers. Think about it. Tiktaalik Lived in a shallow marine environment! Not the open sea. Fins that helped him push through the mud and sand plus lungs for the very shallow region near land gives a limited environment. Food and no competition for insects and plants on shore beckoned the creature. This gives a big advantage to increased ability in land and near land environments. Natural selection here is very unlike the open ocean.
Think of the whales and the dolphins. At one point, their ancestors had legs, feet and fingers. While the remnants of these feet and legs are found in their embryo, and vestigial legs, fingers exist in some marine mammal species, they aren’t functional (kind of like our tail). They have returned to the ocean and haven’t lost their lungs - yet.
I’m still trying to figure out why men have nipples. I have three, which compounds my confusion.
When I look into the animal world I see that almost all mammals have five fingers with the exception of the 3 toe sloth and some salamanders. Even they can grow an entire new limb complete with elbow joints and new toes.
And how about that snake that has two tiny front legs?
What an interesting world we live in, huh?