Ulcers, fin rot on my koi....help!

[MrsGriff]

Hello,
Needs some advise on what else I can do to help my sick koi.
Here's the specs and background:

1400 gal pond, 25 years old
3 large koi, 25 years old
2 small koi 2 years old
1 gold fish
Two waterfalls, one bog and one mechanical filter, one skimmer....and I've just added a uv light.

I bought a API water test kit and have been measuring every three days for 3 months now. All levels seem within range. Once in awhile the alkalinity is on the slightly lower side. I also have test strips that show water hardness is a bit high and alkalinity is a bit low, but I'm not sure how reliable the strips are.

The pond was pretty green in January and I had not done a water change since last September. Bought a uv light and changed the water. Also cleaned out the bog filter. The water cleared. I then noticed that one of my large koi had an ulcer, another had fin rot, and all were flashing.

I'm new at this, but read and watched every how to video I could. Here is what I've done so far:
Added salt up to .07 for three weeks (no improvement)
50% water change and added PreziPro for 4 days (for suspected parasites)
Then 25% water change and have just added first dose of MelaFix, and will continue daily for 6 more days.
Salt is currently at .05
Water is still pretty cold...about 40 degrees.

They have stopped flicking, but the wounds are still hard to look at. Poor babies. :-(

Please tell me what else to do. Closest fish vet is 3 hours away and not an option.

Is there medicated food? Vitamins? They seem to be eating the winter pellets, and they all appear to be fine otherwise.

Attached are some photos.

Thanks!

 

[GBBUDD]

i have used stress coat with great success for ulcers it's basically aloe

 

[mrsclem]

I had several fish that were very bad several years ago. Used a combo of Melafix and Pimafix. They are designed to be used together.

 

[Lisak1]

Oh that's sad to see! I hope you find something that works. Many koi keepers have moved away from salting the pond as it can create parasites that are basically immune to the salt treatment. Instead you may want to try a salt bath for each affected fish in a separate tank. However, the idea of salt on an open wound sounds terrible to me - I think I'd go with the stress coat or even straight up aloe instead.

I know this is hard to hear, but your fish may be suffering from an overloaded pond - 1400 gallons isn't big enough for 5 koi. As they grow, they continue to stress the system and in turn stress the fish.