Did your game cameras capture footage of any herons or kingfishers around the pond?
If the fish came from the stocker then it is possible that the stocker stocked more than you bargained for?
If you can get a current sampling of 4-5" fish that were from the original stocking then we may have a theory that is supported by the facts. Can you put out more stationary fish traps? Try fishing for sunfish with tiny hook and worm?
The sooner you know the answers to these questions the better we can help you decide if you will meet your goals or if you have been dealt a change in plans by the invisible bucket stocker, raccoon who dropped both a male and female adult fish at the same time, or if a GBH burped as he banked over your pond.
Trust me, we aren't picking on you, it just seems all bodies of water have fish show up in them and we all have our ideas how it happened. I would have been in your camp insisting that bucket stocking isn't possible, but later I found out that it does happen despite our best intentions.
The good news is that if you find fish mature enough to spawn and your growing conditions are good enough that you can get this much growth this quickly then you will be having a bonanza of fish and will have plenty of interesting balancing dilemmas in the future as you plan for your future predator/forage balance.
Keep us posted with pictures and your trap experience. Galvanized Gee traps painted in earthtone colors are good. I have had some good success with some cheap ebay pyramid and circle style minnow soft fabric mesh traps for all sizes of fish.
