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what is eating my koi?!

Posted by miketb31 none (My Page) on
Wed, Mar 6, 13 at 23:37

Normally during the winter I can see the koi in the center of the pond, under the waterfall, barely moving for hours due to the cold temperatures. Monday morning I looked outside my window and noticed all 10-12 fish missing. ZERO seen. I run outside and check the filter. 4 fish lay there dying in the filter (we have never found even the smallest fish in the filter, for the large koi to go in there they were surely desperately looking for cover). One 12" koi covered in blood. The large 16"+ koi had his fan tail side fin ripped off. Surprisingly I found the fin OUTSIDE of the pond on the brick! He looked like he was poked in the head. Being the largest fish of the pond but severely beaten up, I was almost positive it was because a heron was not strong enough to lift him out. So I nurse the 4 fish back to life. By the end of the day all 4 seemed like they would live, not sure how long til the stab wounds would become infected and lead to death, but at least live for a little. I then secured the net a little better before bed. I wake up in the morning. SAME PROBLEM! I can't see one fish from our second story window. However, this time I check the filter but there are no fish there! I figured they died and got sucked into the filter, but that was not the case. I walked around the property and did not find any remains. It started snowing at 6am, so by the time I noticed they were gone at 9am, snow covered the ground. There were no animal tracks so it had to occur between the hours of midnight at 6am. We are completely dumbfounded how the net did not appear disturbed. Originally I figured a human stole the fish, but they would not have injured the fish, then returned a 2nd night to get the larger, dying fish. I feel as though a raccoon would have left scraps. A cat would not venture into the water either. Now comes the crazy part. We call my neighbor because he too has a koi pond. He tells us that 2 weeks ago all 30 of his koi disappeared from his pond!!!!! He said originally he figured a human as well, but his dog would have noticed. They he mentions that it may be a weasel or mink! Now living in south central PA (south of Harrisburg) I was unaware that there were minks in the area?? But it makes sense because they could swim in the water to get the fish. However it still doesn't explain why we didn't see any scraps other than the fin of the large koi. Could a heron clean out 2 ponds worth of koi or have you heard of minks eating koi in the middle of winter. Also would a heron feed at night?? Ughhh this is insane.

Follow-Up Postings:

RE: what is eating my koi?!

There are birds that feed at night that live in the Northeastern part of the country. Also, bear in mind that during this time of year, birds are starting their migrations so birds that are not from our areas, could very well be passing through.

My question to you - on the second night, what type if disturbances did you see with your netting?

I am also wondering what you and your neighbor typically do to dissuade blue herons from invading your ponds? I have found that a sensor sprayer does a lot of good - however, given the time of year, it seems early to put out a sprayer.

Here is a link that might be useful: Black Crowned Night Heron

This post was edited by carolyn22 on Fri, Mar 8, 13 at 9:23

RE: what is eating my koi?!

I am so sorry. We had a clear pond where we could see all 7 koi 3 weeks ago.. Now the pond is cloudy, We found a pool of blood outside the pond. A few days later a whole fish intact surfaced floating. The pond is 58 degrees the filter is running . All water tests show the water is in good shape. I can't see a single fish. It is cloudy and green so I have treated for that, still nothing after 4 days. So upset we do not know if there are any fish left inside the pond. How can we tell if there are or not? (LOST)

RE: what is eating my koi?!

Maybe use a game-cam to see what it is? We just put ours out to see what's been messing with the fish, and have seen a couple of pictures of a cat coming around.

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