Spotfin shiner, bluntnose minnow or banded killifish are the three best native species that aren't typically stocked in ponds but are great forage fish to consider. Maximum sizes for all are around 4", all can spawn in ponds. All are more resistant to predation than FHM with spotfin being the most resistant, followed by banded killifish and then bluntnose minnows IMOE. I know of only one hatchery that sells bluntnose minnows and one that sells banded killifish. I know of none that sell spotfin shiners. So you would have to source them from the wild. Spotfin shiners are very similar looking to GSH to the casual observer.