Koi on side with reddened face and body areas after spring cleaning

[Koyper]

Hello, thank you in advance for any help advice.

I'm in Door County, Wisconsin and have a 450gal. pond that has four koi in it, the largest is a female about 16" in length. I'm two hours from the nearest aquarium store, and no vets anywhere near me who treat koi.

These four have been through at least seven winters. I keep an aerator going all winter raised about a foot off the bottom with a deicer when it dips into the teens.

Four days ago, I installed a Oase 5000 gravity filter to replace the troublesome pressure filter I have been using. At the same time, I netted out sediment in the pond. The temps had gotten into the fifties, so I ran the new filter for about six hours before turning it off due to the approaching nighttime temps getting into the twenties.

Two days later (yesterday) I noticed "Skipperette" listing on her side and in a weird location in the pond near where the pump had been just placed (removed last fall for the winter). When I touched her, she would swim forward, but settle soon back on her side. The other three fish are acting normally.

The water quality had gotten worse since I had to stop the filter due to the cold temps. Yesterday it was up to forty, and I was concerned about low oxygen so I put the aeration stones on the bottom, added 5-10% fresh water and put the filter back on. After about five hours, she had righted herself and moved across the pond to a different location.

I was very concerned about her anyway, and took the 1-3/4hr. drive to Green Bay to the nearest aquarium store and got my water tested: ph 8.2, 0% ammonia, nitrite & nitrate. I fallibly was hesitant to stress her out to take photos of her yesterday since she had righted herself, so missed the opportunity for the store to advise, based on the visible reddening I discovered this morning after finding her on her side again.

The store owner (without the benefit of these photos) thought my disturbing the sediment while not lowering the aeration might have caused an oxygen drop.

I have a Zeiss microscope, but have never done a scraping. I have also used clove oil once to anesthetize a fish.

Given the correlation with my pond maintenance and this issue, could it be caused by stress? Or could stress have made the fish susceptible to infection?

I do not have a hospital tank, but could put something together with another many hours drive to the nearest Target/Walmart. If this is recommended, how many gallons would the tank capacity need to be for a fish of this size? I have a large blue Rubbermaid container, but it seems slighty too small.

Any advice would be greatly appreciated.

[fly4koi]

I would aerate the water as much as you can, maybe do a 25% water change. Sometimes when you clean the pond you disturb the sediment and can cause it to release sulfur, does the water smell funky? And if weather permits, run your filter. Can you test for KH? 450 gal is not enough for 4 koi.

[Koyper]

I actually recomputed the pond capacity, and it is about 650 gallons - still probably borderline for the four koi. The water did not smell of sulfer, but for sure I kicked up sediment when cleaning.

We're going to drive her the two hours to Green Bay to Gentle Vet, but at this point I'm not optimistic about her chances. It took a while to find a vet with koi experience, and they are the only one for many hours around here.

[richtoybox]

Get yourself a complete test kit, preferably drop type like the API kits, ammonia, nitrite, high range pH, and KH. If you are going to transfer, be aware that oxygenation is mandatory, a fish of this size will consume oxygen and suffocate if not aerated fairly heavily, or bagged with pure oxygen. I would keep the filters running full time now, and with a bead filter I would raise the KH to well over 100ppm, even as high as 200ppm, until the ammonia and nitrite are both zero. Turning the bead filter on and off prevents the bio bacteria from populating the beads as they use up all oxygen when the system is off, and have to start over the next time it is started.