Posted BySteve Gray on October 14, 2003 at 23:12:18:
In Reply to: My fish were ruffed up! posted bySandy Rodriguez on October 14, 2003 at 11:56:16:

Do you have plants in your pond? If so, don't follow these instructions unless you plan to remove the plants first.
Add salt to your pond to get your water to 0.3% salt solution. To get to this percentage, add 3 pounds of salt per 100 gallons of pond water. This will be 21 pounds of salt for your 700 gallon pond. You can puchase the salt from almost any grocery store in a 40 pound bag for about $4.00. Get the rock salt, if available. Read the ingredients and make sure it DOES NOT contain Yellow Prussiate of Soda (YPS), which is an anti-caking agent.
When you add the salt to your pond, put it in where the water is moving the most rapidly, or predissolve it in a bucket and pour it in. I mentioned earlier to remove your plants because some plants will not do too well with the salt in the water. A test kit can be purchased from pond shops that tests for salt concentration. Consider purchasing one. The last one I purchased cost about $12.00.
How salt works: salt stimulates the fish's mucus-producing "goblet cells" in the fish skin. The additional slime produced by these goblet cells helps cover the wound, kind of like putting a bandaid on a scrape.
For additional information, visit Dr. Johnson's, DVM, webpage shown below.