Poorly koi

[Kimberleyc]

Had a couple of koi who were isolating and off food. Water parameters all good so did a scrape and couldn't find anything (I'm a novice).
Noticed reddening on one so took her out of the pond to have a look. She had an ulcer. Took her to local koi dealer and was diagnosed with costia, trich and a few flukes. Ulcer was treated and a treatment plan for parasites. Treated for costia 2 days ago as priority
Koi dealer said she should survive but shes mostly laying at the bottom of pond and not eating. Not on her side and swimming about occasionally. Any suggestions please

 

[Lisak1]

Size of pond, how many fish, what kind and how big,, how old is pond, what type of filtration? Any info you can share about your pond will be helpful.

 

[WaterGardener]

What costia treatment did you use?

 

[Kimberleyc]

5000 ltrs, 2 koi and about 15 goldfish including babies. 3yr old pond with oase 16000 box filter, also bog filter. Water parameters spot on but have a problem every spring with frogs
Koi has been scraped and diagnosed. Used formaldehyde and malachite for costia..not pre mixed
Lost one koi this morning, the other looks a bit better but not eating

 

[Kimberleyc]

What costia treatment did you use?

Formaldehyde and malachite, not pre mixed. Have done one treatment, due another in a few days

 

[WaterGardener]

My understanding is that treatment should be done 3 days in a row, with a 25% water change between treatments.