My neighbor has very similar pond to mine. Same depth and size also with no aeration - he says his is fine. Weird. I did drop two large trees onto the ice - about 20 inches in diameter - (They were like three feet below the water line and dead, so just used the ice as a way to easily cut them down) . I wonder if the vibration from the trees hitting the ice did any killing? Probably a stupid question, but it was probably quite a shock to the fish when the trees smacked the ice.
I am not sure if different types of fish are effect by this shock but I have seen this before too. My buddy came back from his trip to Costa-rica and noticed his koi pond frozen over. He panicked and pounded a hole in the ice with a hammer. In the spring every fish even all the small baby's were all dead. Was this from low OD for the week he was gone or from the shock?
Don.
