For us we didn't see any FHM stocked the first year. Just a couple of dead ones from stress. It wasn't until the next season until we saw schools of babies swimming near the surface.
With that many stocked FHM, there would likely need to be more than one predator in there to clean them out. You surely would have caught one by now as they would be hungry once the FHM were consumed.
I would bet they are still in there. I have been trying to trap FHM in my pond to transfer a couple into my garden pond which is a mosquito heaven right now, and having zero luck with bread. I see them occasionally swim right by the bread and trap. I am starting to think the traps only work for ponds with so much life density that the minnows trip and fall in.
My next try will be putting some fish food in a piece of thin material the fish can peck at. Bread isn't working at all for me. Otherwise bait shop here I come.
