For the naysayers, explain this one.
This happened in my new excavated pond with no water source inflow other groundwater and 3 or so acres worth of yard runoff. A year after completion and the pond was a little over half full, nothing had been stocked yet, I saw what looked like cat fish rolling at the surface. My daughter and I set out some lines with catfish bait and caught several 8-10" CC. No one has access to the pond without a visit by my two bullmastiffs that roam the property so I doubt they were put in by people.
