I have small pond 40 ft by about 100 ft, deep 8 to 6 feet across. This Spring friend of mine gave me about 10 common carps. The size is from 12'' to 16'' or so. They been doing great, eating and growing all summer. About month ago I found one big carp dead. I assumed it's rotten leaves issue and started to aerate 2-3 hours at night. It was some ice, but weather was mild. I found one more dead carp week later and started to aerate whole night. I have pretty powerful 1.5 HP pump for the size of my pond. Couple days later I found 3 more dead carps. So, DO was not apparently the issue. I stopped aerating but week after found one more dead carp. They appeared healthy, no spots or parasites that I can see. I have some bluegill and several Large Mouth . Non of those seem to get affected.
I'm devastated. Those carps survived one hour trip in trash containers with little water, hot weather, fall floods, herons visiting the pond and now dying like crazy. Water is crystal clear. Pond is fed by spring that goes in on one side and excess water is coming on other side.
My first thought was that I dropped temp too much melting all the ice with aeration, but fish is still dying with no aeration at all.
Is there anything I can do at this point? Why do you think fish is dying?
Thank you for advice.
