Salt is the most commonly recommended treatment for parasites

Dr Erik Johnson recommends that you use salt, before you try anything else for parasites for the following reasons ...

1) harmless to almost all fish

2) even if it does not cure it does not kill sick fish

3) most parasites are killed quickly

4) has little if any impact upon most pond systems and their bio filters and is unaffected by weather

5) safe to humans and animals

6) low cost

Salt kills these species ....

Ichthyophthirius

Chilodinella

Costiasis (Ichthyobodo necatrix)

Most Trichodiniid/Tripartiella organisms.

Glossatella

Scyphidia

Epistylis

Trichophrya

External Tetrahymena

Inhibits trematode reproduction, clears 30% of adults.

Inhibits Lerneiid reproduction

this reference source is Dr Johnson of Koivet.com

Salt Dosage:between 0.1 and 0.3 percent depending on severity. Take advice from specialist advisor if unsure. The salt should be non-iodized food grade and should be added in 3 lots spaced out at intervals of about 12 hours.

Remove pond plants.

Please also check out this UK Pond Doctor site

What to do if you suspect disease problems

Test for Ammonia, Nitrite, and pH at a minimum, and preferably also test for Total Alkalinity and possibly Hardness.

Ammonias are lethal in their own right and worse at higher pH. If dead fish exist this will also create ammonia problem. pH can change overnight if the system loses its buffering capacity (this would show on a test of Total Alkalinity)

Aquarium Pharmaceuticals basic drop type test kits are most accurate according to experts. Review USA on-line pond supplies

In the case of Ammonia accumulation:

If water quality is suspect begin a systematic daily changing of 20-40% of the total volume in the system. But beware of major temperature changes the system. A small addition of salt at .1% level will do no harm.