Jack Koi has a bent tail! New photos

[miguynmkoi]

I have had Jack Koi for almost 4 years.  He has always been shy and grabs food quickly and disappears.  About a year ago I noticed his tail was slightly crooked, pointing up.  He was about 3+" long at that time.

 He has grown about another inch since spring and gaining more weight.  The past few weeks after I relocated many of the fish from the pond I noticed his tail slowly getting more bent, upwards.  During the past week (acceleration) his tail is almost 90 degrees turned up and he has difficulty swimming straight unless he goes slowly.

Like I said before he is a skittish koi and now when he tries to swim too fast he goes in circles for a little while before he stops then slowly wiggles away.  When he is still I see he can still flex his tail fin. 

All the other fish are fine.  I feel bad his tail is bent and he swims in circles.  Will this go away if it was an accident?  Or is this like a deficiency that affects the spine? 

Photo of Jack in March.  I'll see if I can get another pic today of Jack with bent tail 

[Sunbeam56]

Sorry to tell you this, but I've had to do a lot of research on bent tails/backs. There are a lot of causes, but mostly, they do NOT get better.
In 1999 I took 11 koi to Gardena, California for the koi show. When I got back, 9 of them had deformities. Whatever the cause...
I put my faves in a SMALL tank for the rest of the winter. They were mostly siblings.
"Fido" outgrew the deformity, and is a producing male tancho showa.
"Dot" never outgrew the deformity, and is a lovey but twisted shiro utsuri.

We sacrificed one for testing. Didn't find anything conclusive.
And the rest have died for various reasons.

Twisting of the spine is either a severe genetic deformity (rare), or a severe trauma to the spinal cord. (not rare - too many sources)
Either way, they rarely recover.

[lorraine1960]

still beautiful....lorraine

[miguynmkoi]

I guess there is no good news.  Oh Jack, I guess I'll love your bent tail any way!  Just hoping he doesn't suffer too much. 

[Jonna]

I have a Wakin in the pond in Calif that has a bent tail.  She's fine except that she is the one I had to rescue from her suitors last year.  I hope she made it this year on her own.  She can't swim fast enough and they were beating her up.  Let's hope Jack Koi is really Jack and not Jill.

[miguynmkoi]

  That would be a problem    So far all the koi in my pond seem to be neutral.  No chase no matter the conditions, etc.

Right now if Jack isn't spooked he eats well but when scared he becomes a whirling dervish with no control!

[Sunbeam56]

I don't think that tail will straighten. But you can improve his muscle control, which will give him less of a panic.
Put him in a SMALL aquarium. That is, rest him and encourage him to grow. Baby koi will grow very rapidly if they are treated like plants, fed and watered regularly.

As he grows, he may outgrow the deformity.

What we found was that where the spinal defect was, the fish grows normally from the nose to the defect, but there will be some atrophy of the muscles behind the defect. So when the front of him is bigger than the back of him, he should be able to move more normally.

We also found that in less severe cases (not Jack, unfortunately) the body seemed to compensate. Like with Fido. You can't tell he ever had a crook. Either the surrounding nerves took the load, or the nerves regenerated.

[miguynmkoi]

As he grows, he may outgrow the deformity.

Thanks Sunbeam!  Your advice sounds good for Jack.  I will keep him in a small QT and hope he will be happy.