I've fished this system my entire life and talked to hundreds of others who also have, and have yet to see any evidence of any shad. They are not present in the system. The lake is not usually stocked with forage fish of any kind, hence why there is a very low population of bass, but high population of bluegill, pumpkinseed, and bullheads, which subsist mainly on swamp crayfish and other inverts, as well as food thrown to the ducks by people. There are, however, a small number of golden shiners in some deeper regions of the lake.
I also held the fish in my hand and examined it closely, and noted it to be characteristic of a cyprinid, most likely a shiner. In doing so, I ruled out it being a clupeid. Even if you cannot do so by the pictures because you cannot see it clearly, I have.
It's 100% not a shad. I dont know why this is difficult for you to grasp.