It looks like something tried to eat him. I have one that lost the top half of his tail and a few others that were wounded this year. None were actually taken from the pond so I don't think it was a heroin or coon as they are more efficient killers than that.
Yours looks like his spine was broken in the attack.

Thanks for your reply Mike ,

I don't think it was attacked in any way for I have NEVER seen an open sore/wound on this fish .
I keep a close eye on them all as much as I possibly can .

First noticed this fish laying on it's side on the bottom of the pond back in Feb. of this year.
It was very cold then but I medicated the pond and hoped for the best..it survived the winter.

Come warmer weather in the spring it rallied and I
then noticed what appeared to be a small bulge on one side of it .
Now that bulge has seemingly gotten worse and is resulting in the extreme curvature you can see now.
Perhaps I was actually seeing a " curve" vs. a bulge back then but not sure .

Such a sweet fish, very "personable" if you will.
Hate to lose/cull it, just am wondering if it possibly looks like a tumor or something else ( possibly treatable ) to anyone that may have dealt with the such ?

Thanks again !

This post was edited by love2gardenn on Sat, Oct 12, 13 at 0:30

I'm not entirely sure that this is the cause. Koi, like anything else, are prone to cancer and tumors. If the tumor is putting pressure on its spine, it would cause a deformity. Love, I totally understand how you feel about losing a fish. I could never be a breeder, because I can't destroy something for the way it looks. I don't know how much science has come along in the ways of koi cancer. Sorry for being the bearer of bad news.

thanks Craigger, I prob. will put the clove oil to it mid winter, will see how it goes.
I am not a breeder of these fish either , just a hobbyist that loves them and hates to lose one like I did today.
getting ready to start another post about that one shortly.

Has the koi been in a net lately? moved locations?

I was offered the opportunity to take all the fish from a small pond shortly before a couple moved. I netted out a couple of beautiful comets and about 30 2-3" baby koi. Of the 30 koi, probably 12 or so had a similar condition. I never found out what the cause was, but I euthanized the deformed koi and gave away the others. I've always wondered what might have been the cause.

Thanks for your input pcan and rsingley.
This fish has not been netted or moved but that's a good possibility of a cause in some cases, I would think.
OR, it possibly was injured during the breeding process, those fish can really " go at it ". lol
Or, it does have a tumor.
It has begun to stay on the bottom of the pond in one place
more now , not moving around much while
However, it comes up to eat and jumps around so vigorously in doing so, seems like such a " happy " fish other than this problem.
Kind of reminds me of a pup wagging his tail and getting excited when it's dinner time.
Like I say, it's quite personable, sure don't like seeing it "Handicapped" but sure cannot afford a speciality vet to look at it either.
Thanks again , any and all input greatly appreciated !

This post was edited by love2gardenn on Tue, Oct 22, 13 at 11:35