[RayJordan]

Lots of information, some good - some bad, on the web about the use of salt in koi ponds. I had someone call me that had been having a running battle with ulcers on their koi. They had tried everything reccomended on the message boards except getting a scraping under a microscope to determine what type if any parasites their koi might have. I figure they spent enought on meds to buy several scopes.

After buying an entire fish pharmacy and dumping it all into their pond they were not seeing any new ulcers but the old ones were just not healing. I made a pond visit and the usual water tests seemed OK. I scraped and found no paracites (which wasn't surpising considering all the different treatments they had tried). There were some nasty looking ulcers on several koi that I was told had been there for months.

Next we caught the koi with ulcers and I noticed they felt like sandpaper. No slime on these koi at all. After showing them how to clean, treat, and seal the ulcer of the first koi I watched them treat the rest. Then I tested the water for salt. It tested at 0.8%. They had though they were adding enough salt to get to 0.3% after water changes but did not have a salt test kit and I think their pond volume was much less that their contractor had told them. I had them do a 50% water change that same day and another 50% a few days later. I had them buy a salt test kit and told them not to add any more salt and let routeen water changes flush out the remaing salt.

It has been about three weeks since my visit and they just called to say all the koi were healing nicely and no new problems had occurred.

Salt is not a harmless tonic. It will definately inhibit wound healing if used at too high a dose(above .3%). It will hurt your biofilter and kill your ponds algae coating and cause a major crash in water quality as a result of rotting dead algae.

Use salt for a short period of time for a specific purpose.
0.05% to 0.1% to reduce stress (few days to 2 weeks)
0.3% to 0.6% for a treatment of protozoan paracites for (two weeks max)
be very careful about using salt in combination with other water treatments.

If you use salt you must use a salt test kit to insure you are getting the right dose.