Koi is currently spinning in circles

[MitchellC]

my grey koi in my fish has, what it seems to be, a bent spine horizontally and so whenever it swims it barrel rolls. It can’t eat or move or anything so if anyone can help it would be much appreciated. A photo should be attached

 

[Jessie J.]

If it's a curved spine and he can't eat, the best option is probably to euthanize. But if there is a way he can be saved (I'm unaware of this but someone else may know if you can fix it), put your hand in the tank with a pellet and hold it right in front of his face so he has a chance at eating until corrective measures can be taken. But, as mentioned before, I don't know if there's a method or not and if there is it would require a trip to the vet and risky, expensive surgery.

 

[Colin_T]

If fish start spinning, spiralling or barrel rolling through the water they normally have a protozoan infection in the brain. This is most commonly found in dirty tanks or ponds with lots of rotting organic matter and lack of water changes.

The fish in the picture also appears to be skinny and that can be from lack of food, gill flukes, intestinal worms or protozoan infections.

Try doing a 75% water change and gravel clean the substrate each day for a week.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

Clean the filter if it hasn't been done in the last 2 weeks.

If there is no improvement after a few water changes then euthanize the fish.