I live in N Alabama, 30 minutes from one of the top 10 bass lakes in the US - lake Guntersville. This lake is over populated with gizzard Shad. I have caught many of them over 12 inches and twice as wide as a Golden Shiner. They are controlled by monster LMB and Stripe bass which can get over 50 lbs in this lake.
I would love to stock my pond with threadfin shad but in a small pond, the gizzard shad would eat everything and take over. They are aggressive eaters and grow too big too fast for most small ponds with BG and LMB.
If I owned a lake over 10 acres, there is no doubt that I would add Gizzard Shad. In my observation, most trophy lakes in the south have gizzard shad. As for threadfin shad, they are just too delicate to keep alive. Shiners and crayfish seem to be the best option for small pond owners.
