My neighbors pond had a fish kill over last few days. Aprox 100 floating bluegill and crappie.Very few bass. No small fish all over 6 inches. One crappie still alive had cloudy eyes. also bloody around dorsal fin and scales. He thinks its runoff from a sprayed bean field. I think its a localized decomposing growth and the fish were gassed and had no oxygen.
A bloody looking mucous sounds like Columnaris, which is bacteria that is always present. Stress allows it to become an infection with near total mortality rates on susceptible fish if left untreated. Potassium Permanganate is available, reasonably priced, and easy to use in large bodies of water. It will turn the pond a deep reddish purple and needs to be dosed accurately.
Treating is pretty useless however, if not discovering and correcting the original stressor that caused the outbreak.....
