Hi! The fish in the picture definitely has fungus and likely has a bacterial infection as well. Fungus is opportunistic and usually only affects fish that already have a bacterial infection or have suppressed immunity from poor water conditions. The over zealous cleaning most likely threw your ponds water parameters out of balance. I would suggest atleast taking a sample of water to be tested at your lfs
. I'm not home so I don't have any of my links but I would suggest checking out some pond suppliers for a decent antibacterial/anti fungal pond treatment as well as some water changes.