So with the warming weather my main pond which is 4 ft deep is now fully de-iced. The water us crystal clear and yo my dismay all my koi are gone! Big dead, no remnants, nothing ...I mean not a trace! These guys were 6 yrs old and well schooled in survival. I keep an aerator go allow gas exchange in the winter every year. My guess us a raccoon, but my dogs patrol the yard going ballistic on anything in their yard night or day. Oh well, but it still is a bummer, like I said 5yrs and at least 2 feet long.