I live in new jersey, and seeing that the leaves are mostly off the trees, yesterday i decided to pull the net off my pond. My pond contained 9 koi and numerous small gold fish and comets. The net covers mostly all of the pond, with the only openning being the area accessable from underneath my deck. Upon removing the net, i unfortunately found 2 large koi floating on the surface, a carcass of a koi near my filter, and a lot of carnage in the area unprotected from the net at the base of the deck. (mostly lots of scales). As the water has cleared up, i notice that i have not a single koi of the 9 left, yet all the small fish (comets and a couple small pond breeded koi) are still fine. I am just wondering if it's possible an animal got to all of my large koi? Seems like that wouldnt' be possible since they are mostly bottom dwellers in the cold fall/winter, and any predator, I would think would have to actually enter the pond, swim under, and grab them. Does it seem more likely for this to be the case? or some water quality issue? Right now the water is about 40 degrees, and I just tested (NO ammonia whatsoever). Are the big, basically dormant fish a much easier prey than the small ones? I'm very distraught about loosing these 9 koi.. many of which i've had for 5 or more years. Any advice or information would be appreciated. Thanks so much.. Mike