What disease might this be? (2PICS Included)

[Miga Milan]

One of my koi died today. Yesterday I noticed an irritation in the section where body meets tail yesterday afternoon.
Two other koi are lethargic and not eating much today.
My water/chem levels are within normal range.

 

[Meyer Jordan]

Please be more specific on water parameters. What are the numeric readings?
The symptom that you show in the photo could be an indication of several different things.
Does this mean that you presently have 10 Koi remaining?

 

[Miga Milan]

PH 7
Phosphate 0
Nitrate 0
Amonia 0
Pondcare master liquid test kit
Water temp 82F


Lost another fish today. Now Im down to 9 remaining koi. This 2nd koi shows no visible lesions physical abnormality. She had been hiding and not eating for the past 24 hours (spawned 4 months ago). I have a 3rd that looks a bit spaced out too. The other 8 are acting and eating normal.

 

[Miga Milan]

Started Feeding w Medi-koi.
Did a 50% water change Monday afternoon.

The disoriented koi was not able to swim. Kept flipping from side to side. But is doing better since yesterday morning. She is swimming okay but a bit slow. Also, she behaves as if she wants to eat but is not able to see the food. So not eating at the moment.

 

[Faebinder]

Sounds like internal parasites. Medicated food is the way to go and isolate sick fish if possible.

 

[LibraKoi]

Sounds like internal parasites. Medicated food is the way to go and isolate sick fish if possible.

What type of medicated food for internal parasites?

 

[mrsclem]

LibraKoi- this is a post from 2017 and since then, medicated fish food has been removed from the market. There are still medications available that can be used in quarantine tanks.