Salt: Remove submerged plants. Perform a fifty percent waterchange, and clean the pond as well as reasonably possible without causing undue delay in treatment. Apply one teaspoon of non iodized table salt per gallon of water every 12 hours for three treatments (3 tsp per gallon). Alternatively, for larger systems, dose one pound per hundred gallons of water every 12 hours for three treatments (3 pounds per hundred gallons). Add all at once in the case of epidemic mortality.

Salt is a superior remedy for many different reasons, many of which will show up in a search of this website and in the book I extoll this remedy even more.

Kosher salt, Sea Salt, Non-Iodized Table, Rock and Ice Cream Salts are acceptable. Do not use salt intended for livestock if it contains any minerals or trace elements.

Caution! No YPS or Yellow Prussiate of Soda should be in the salt. Prussic Acid is hazardous to fish because it dissociates into Prussic Acid in water!*

Add the salt all at once if fish are dying off rapidly

Add one pound per hundred gallons, per day, for three days if fish are merely sick. This avoids occasional filter-shock. (2-3 day nitrite spike)

Will not harm hardy Lilies, common Papyrus, or Irises. Will cause yellowing of Hyacinths, Celery and Water Lettuce, but will kill Anachris, String Algae, Cabomba and Elodea.

Strengths
3 pounds per hundred gallons = 0.3%
6 pounds per hundred gallons = 0.6%

Pull sensitive plants to baby-pool and treat with Formalin in this. (25 ppm 8-12 hours)

Leave salt in the pond for 14 days minimum, then remove by partial water changes over subsequent weeks.

• Note From Doc Johnson
  "I am always absolutely sure to read every ingredient in the salt I am using. I do NOT take it for granted tha my time honored favorite brand of salt is still being made with the SAME anti-caking agent as always. They *do* change these ingredients occasionally and the addition of Yellow Prussiate of Soda (YPS) can cause death fairly rapidly in soft water!" ~ Doc Johnson

More on salt...

Astor, Akso Nobel, or Morton brand non-iodized salts sufficient to treat one system to 0.3% two times. Most any salt is okay if it's not: YPS laced, mineralized, iodized, or really dirty. I've used animal feed or licks - "salt blocks" from the feed store with excellent results, you need to read labels and look for 99.5% purity with no trace minerals. The blocks are easy to store and transport. Put them in the way of the water return and they dissolve rapidly. NEVER put salt into the filter intake. The sudden rise in salinity will annihilate your filter bacterial function. One man local to me put fifty pounds into his skimmer, straight through the filter, and made his beads snow white.

*It was funny the other day I was reading on a famous British message board someone was pontificating about how YPS salt would cause deaths in fish by forming cyanide in the water. They were absolutely sure. Did you know that the risk of that, apparently only happens at like; three thousand degrees Kelvin? About the temperature of the sun? Yeah...By the time the fish pond gets to the temperature of the surface of the sun, the fish will have a LOT more to worry about than the salt.

There's a lot of crazy notions that come from uneducated interpretation of some big fat books, on some British message boards and even here at home. Of course there are also great truths, my favorite is the thread about ionization constants for Nessler's reagent tested Ammoniacal compounds as measured under a variety of oxygenated and pH regulated environments interpreted within the context of the validity or eventually decided invalidity of the Michalis-Menten equation. You know, really useful stuff for the hobbyists. LOL !