Salt is used as a parasite prevention and treatment, primarily spring and fall, or if symptoms are noticed during the summer months. Symptoms include flashing, jumping, gasping for air, reddened fins, lesions, erratic swimming, fungal-looking infections, malnutrition, excessive slime coat, and fish deaths.
The recommended dosage for salt is 0.3%. At this solution most emerging parasites will be killed. However, many plants in the pond will also suffer and die at this salt level, so it is advisable to remove all plants, wherever possible, before adding salt to the pond. In ponds where it is not possible to remove the plants or to lower the water below the level of the plants for the duration of treatment, it is recommended the salt level not exceed 0.1%. (At 0.3% this would be 2.5 lbs. of non-iodized salt per hundred gallons of water.) It should be administered in small, dissolved increments until reaching the 0.3% level, over a 3 day period. A salinometer is a very handy instrument when using salt.
For free-swimming and external parasites, 2-3 days would be sufficient to kill most populations. For parasites such as ICH, which is a ciliated protozoan that encysts under the epidermis of the fish and cannot be eliminated until free-swimming, the time frame for salt use must be extended to allow the life-cycle to process over 5+ week period, depending upon the water temperature. (It is roughly 2-5 days in warmer temperatures but can be up to and beyond 5 weeks in cold temperatures.)
One of the benefits of salt is that it is one of the safest treatments for the hobbyist to use and least harmful to bacteria in the filter.
NOTE: Salt is a chemical and overdose is possible if not used with care. These are fresh water fish, not salt water or brackish-water fish, so salt should be used in moderation. To use salt all year will serve to promote salt resistant parasites.
NOTE: Also, when using salt in the pond, it is important to have a way of removing the salt from the pond. It can’t be discharged onto the garden, so a purge line directly to the sewer or other appropriate receptacle should be planned beforehand.
a.. Salt is used to increase the slime coat at times of stress.
b.. Salt will regulate osmotic balance to reduce stress.
c.. NEVER USE IODIZED SALT. Always use Non-Iodized table salt, Kosher Salt, Water Softener Salt, or Sea Salt in the pond.