Hi All,
Been a bit since I posted.
I recently did my spring pond maintenance and health check of my fish 2 weeks ago. During this I didn't not any issues with them. A few days after, while doing a water quality check I noticed one small koi had a torn pectoral fin. This had appeared after it was added back to the pond, and I'm 99% certain occurred during the 3 days between the maintenance and when discovered. I started watching this fish closer and over the last few days it became slightly lethargic. I became concerned yesterday and intended to move it to an isolation tank today to get a better look. When I went out today I found this:
Overnight those growths on its head and pelvic fins appeared. Also, the damage to its tail became apparent. I visited my local pet shop and the owner thought it could be bacterial from the wound and recommended an antibiotic. I'm treating with NeoPlex following the instructions, but curious if anyone with more experience may have some idea what may be going on or something to save this fish?
Water testing over the past week has shown Ammonia to be consistently at 0, Nitrate and Nitrite at 0, pH came in at 8.6 each time but is within my normal 8.4-8.7 range due to water conditions. I've tried reducing that with treatments, but I may as well throw the money in the pond. Phosphate did show a trace at 0.25, which may be due to runoff or the addition of some new plants. As a preventative I did a 30%ish water change today and carefully looked over the other pond occupants. No other fish are showing any signs of stress or injury.