KC :

Welcome aboard the fourm.

Shale can be impermeable {not let fluids through} and act as a seal between over or under lying strara of sands , clays or other rocks. However if it is fractured it loses its impermeability at least as to the length and depth of the fractures. If you have many interlocking fractures it is not much different than gravel. From the pics. it looks like many fractures but that could come from digging. The question is how fractured is the shale in its natural state. If solid and unfractured ( as I guess is the case in existing pond} it may not leak . Also if the shale is uniformly underlain by clay or some other sealing barrier it may not matter if fractured or not. The question of if fractured shale will leak uphill depends on the dip {angle} of the beds { not necessarly the lay of the land}. If the fractured shale bed is dipping up away from the pond then the amount of loss will depend on the water pressure at depth vs. the pressure needed to force the fluid through the fractures at depth and up dip.

If it were my call , as ML stated ,I would add clay or some other sealing material to plug the fractures. I doubt it will leak up dip to much as it apears the limited shale bed is in shallow water and you get that much elevation change quickly uphill. My worry is that it could leake through the shale bed sideways around the side of the pond and then down dip {down hill}. So you may want to pack clay around where the shale is under water and intersects the sides of the pond. That is a guess from the very limited info from your pic. I hope this helps. ewest

PS on your second question most people say that crappie because of their reproductive cycle are nor suitable in ponds under 40 acres. Much dicussion on this fourm about that.