Update on this post - as predicted, my FHM have all but disappeared as I filled the pond the rest of the way and added in some of my initial stocking of WE, YP and RES. I'd guess this is mostly due to predation.
BUT - my little forage pond is absolutely FULL of the little guys! I see at least 3 size classes when feeding....question, how fast will FHM grow if fed regularly and with no predators to chase them around? Question #2 - how many spawns can occur in a single year, under the same circumstances?