I found one of my koi bobbing at the top of the pond yesterday afternoon. I brought him inside and set him up in a 10 gallon quarantine tank. I cannot find anything physically wrong other than two tears in his dorsal fin and a tiny bit of fraying on the bottom of his pectoral fins though I can’t be sure he didn’t cause these himself because of his condition. His right eye may be protruding slightly but it’s difficult to determine because his left eye is seemingly stuck in a down position. He will swim in circles before settling at the top for a while, mostly vertical, and bobbing up out of the water. At times he almost seems like he’s trying to jump out.
I treated with paracleanse (metronidazole and praziquantal) yesterday and added Neoplex today. No improvement so far, seems about the same. I’ve attached two video links, one with the calmer behavior and one where he’s circling around. I have access to other medications if recommended via my vet (he’s not an aquatics vet but works with me to treat my fish when need be).
The pond has been well established for years and houses several other koi and goldfish, some dojo loaches, and some bullfrogs. No other inhabitants are showing signs of illness, only exception being that I found 1 bullfrog dead yesterday (in a separate small pond that does not connect to the main pond). Apparently the bullfrog had tried to eat a wasp, which was halfway down its throat and the stinger embedded in the roof of its mouth. I only mention this in case it’s relevant since there have been a ton of wasps and daubers around the pond this year due to drought conditions so the koi may also have accessed them and I don’t know whether that could be related. We’ve also had 3 fledgling birds and 1 baby skunk drown in the pond earlier this year, for whatever contamination potential there could be there.
This fish was the last of any recent additions back in April following quarantine. All fish were routinely dewormed with praziquantal at that time (I do this twice yearly now after having had prior deaths due to flukes going into the fall/winter).
Current parameters in the pond:
Ammonia: 0
Nitrite: 0
Nitrate: 0
pH: 8.2 (high range api), 8 (wide range api), and 8.5 (digital Hanna)
Temp: 70.1
We’ve had some colder nights and hot days recently but the pond temps haven’t varied in any extremes.
Pond is about 1200 gallons.
I appreciate any input. I’m willing to do anything I can to save him.
https://youtu.be/JfShtSep698
https://youtu.be/pBfhY6rYJg0