Sharon Goode said:
Would you try the salt treatment for a few days to see if it clears up the ulcer on this fish? Catching and isolating him is just about impossible. My pond plants, lights and pumps would have to be removed and then the fray would probably cause stress and damage to the rest of my fish. There is probably another month of decent weather here which would give me time to do water changes and remove the salt levels. This is a 30.00 dollar fish but I have spent many hours watching him grow and would like to save him if I can.
I would do the same as you. I'd look at the problem and do my best within my personal limits to try and improve the conditions. I don't have enough info of your specific situation to feel like I can even suggest a specific course. Best I can do is discuss options you could consider in addition to other sources. This stuff is difficult even when I'm on site...in text messages and pictures...just not reasonable imo. At least I don't feel comfortable.
Understanding I don't remember any previous posts...in general when I hear ulcer my first concern is how the fish got an ulcer. That problem has to be addressed first or at the same time. Normally this means water quality. Trying to cure an ulcer by using salt in the pond that allowed an ulcer to form does not seem like a good idea to me. An ulcer is really more of a symptom. However, the ulcer could be just from a cut that got infected. If water tests look good and there's just a single ulcer, especially if it looks like a long gash rather than a round sore, I'd probably assume injury and just treat the infection. With multiple ulcers, and vary in size like they started at different times, I start to suspect a bigger problem.
If a fish had an ulcer and was valuable to me, either monetarily or emotionally, I would setup a separate tank, a hospital tank, and treat that fish as needed. Gets the fish out of whatever is causing the problem and I can better inspect the fish to see if there's any obvious problem like parasites, or more smaller sores that I had noticed before. I can increase the water temp into a optimal range that increases the fish's own immune system, which that alone I consider the best possible treatment. I can better watch the fish to see if the treatment is causing a problem and reserve the treatment fast. It just gives me some control.
Treating a whole pond you roll the dice and hope for the best. Perfectly reasonable choice if that matches your specific situation and goals.
If the cause of all this was due to parasites I would separately treat the entire pond with some product like Formalin. Salt is effective, but maybe not as effective. Plus it's a huge pain in the rear. I don't like complex if simple is available.
Fish can be caught and handled with little stress. I saw a great Youtube that demonstrated the method in a pond with lots of plants and hiding places, but of course I have no way of ever finding it again.
It's actually pretty easy if you have the right kind of net and are patient. You can remove whatever plants you can from the pond, but that's not really needed. Use a shallow net made specifically to catch koi
like this one. Most people I think don't think this would work because the net is so shallow the fish would jump right out...but that's kind of the point. The idea isn't to catch or trap the fish. Very difficult to chase Koi around any pond or tank and actually "catch" them. The idea is to gently embrace the fish.
Slowly move the net in the water and from behind and below slowly coax the fish to the surface with the net beneath the fish and then coax them into a plastic tub.
Here's a good example, although I wish I had the one with lots of plants.
As you see there's no chasing of fish. Even in a pond with no hiding places you can't really "catch" a koi. They have to allow themselves to be caught. Which they don't normally mind too much, they've been through it many times before.
Having said all that, you still have to work within your own personal parameters. I'm not saying you "should" do this or that.