Sick koi clamping fins on the bottom of the pond

Sick koi clamping fins on the bottom of the pond

   2026-08-28  Posted in Fish, Koi & Pond Fish, Symptoms of Disease, Treatments, Veterinary Care

Consult on Koi Depressed and Covered in White Material and some Sores

“I was hoping you could take a look at some of these pictures and video and let me know what you think. This is not a regular customer but someone who just reached out to us. We tested the water and the parameters tested fine. They did a 50 percent water change a few days before we got there.They have one of those sand filters on the pond which I think is pretty clogged but I would assume the water parameters would test poorly if that was the cause of the problem. I do have medicated food and parasitic and fungal exterminator if that’s something I could use to help them. Right now the food probably wouldn’t help because they’re not eating.  They have lost six fish over the past two weeks. I appreciate your help with this. Let me know your thoughts. ”

Answer:

So I would use that video as a teaching case for low pH. For every single fish to be included, that really matters: Because even in a parasite outbreak, you’re gonna have some fish stronger than others. most of the time in parasite outbreak, you’ll have some fish acting like nothing‘s wrong. And for all those fish to be “down“ like that I’m really thinking of prevailing water quality issue. So I would think seriously about a crashed out pH. So you should double check that, and not take their word for it.
I’m really thinking of prevailing water quality issue.
Because that’s what it looks like.
Something else that might’ve happened, is a massive water changed 10 days ago where they forgot to dechlorinate. That burns the shit out of fish. They’ll suffer with that for a solid week afterwards if they live.
So those old Ultima two filters suck. It’s not a sand filter, it’s gonna have badly compacted plastic beads inside. It’s a shitty, downflow bead filter from the olden days and the cake inside is going to be unbreakable, you’ll feel it. You’ll have to break it up with a trowel. It’s practically doing nothing but OK.
I think they should get 2” of pea gravel in the pond, and have it ANNUALLY maintained and this would never have happened.
If you’re really, really, really really really really* really convinced that it’s not a crashed pH, or a sneaky, high ammonia level, or both, then that’s going to be a parasitism.
If water temperatures are 80 or higher, it’s not ICK  but you can use this particular medicine quite effectively This time of year.
At least double the aeration in the pond. Apply it daily for three days skip a day and apply it one more time and see where you’re at. If the pond water is over 80, any medication can create risk. You might want to drop a hose in there and cool it off a little bit. Make sure you use de chlorinator.
*REALLY
ERIK L. JOHNSON
Johnson Vet Services Inc
3100 Roswell Rd, Suite 113
Marietta, Ga. 30062
TEL (770) 977 5377 • FAX (770) 973 0301

IMAGES and VIDEO of CASE

Author: Dr. Erik Johnson
Dr. Erik Johnson is the author of several texts on companion animal and fish health. Johnson Veterinary Services has been operating in Marietta, GA since 1996. Dr Johnson graduated from the University of Georgia College of Veterinary Medicine in 1991. Dr Johnson has lived in Marietta Georgia since 1976.