Hello,
I recently found this forum and I am hoping someone can help. I'm pretty new to Koi keeping. I recently upgraded to a larger pond about 3 months ago. From 600 gal to 1200 gal. I have not really experienced new pond syndrome except for string alage outbreak due to this pond being in full sun unlike my other that was completely shaded. [Never had algae issue] But I transferred all the decor and pond filters to the new pond to make sure I moved over the good bacteria. My pond has been stable regarding water quality but 2 weeks ago, I had one of my koi develop lesion on both sides of its head in front of gill plates. Then a week ago the smallest of my baby koi died. Fins clamped and stopped eating. It was dead in a few days. I treated the pond with Melafix antibacterial treatment but it was too late for the younger Koi and the other Kois lesions are not getting better- but not getting worse.
Yesterday I did a 30% water to change and added some pond salt but just 3 cups because I'm scared to kill my fish. I estimate my pond has 1200 gal but not completely sure as my water meter failed when I originally added the water and I don't think it gave a accurate reading.
I also added stress coat in the pond.
The koi with the lesion is not showing signs of sickness. Eating normally and zooming around the pond. It did flash a bit yesterday after I did the water change and added the salt. But it hasn't done it again.
All my other koi and goldfish are just fine. The only other thing I can think of is if maybe this Koi got sunburn? It is so hot here in FL. And at first i had no shade but noticed the water was rising above 85 degrees. So I added some cover since then about 70 percent cover but the water temp is still around 80 even with cover.
I am confused what these lesions are and why they don't seem to be healing [but not getting worse either]
Water parameters:
Ph 8
Kh 120
Gh 180
Nitrite 0
Ammonia 0
Phosphate 0.5
Nitrate: unknown. I just learned on this forum I should be testing for this too. Master kit did not bring this test