Q. An article recently published by a veterinarian stated that adding 2.5 pounds of salt for each 100 gallons of pond water will help reduce parasite problems like ich, anchor worms and fish lice. I have had serious anchor worm problems every summer and I wanted to add salt to my ponds this spring. However, some of the “old hands” in our local goldfish club insist that the salt will have no effect. Who should I believe?
A. Believe the old hands. They are right. The concentration recommended by the veterinarian is roughly a 0.3-percent solution. While a number of hobbyist publications have claimed that this concentration inhibits external parasites, well-controlled studies in laboratories and fish farms show that it has no effect of any kind. Indeed, some freshwater ectoparasites actually thrive in slightly salted water.
It is true that salting the water stimulates the production of fish slime, which has some degree of anti-parasitic effect. But it is not significant. Think about it: If fish slime was so toxic to parasites, there wouldn’t be any fish parasites. A number of ectoparasites actually live off of fish slime, as do a number of pathogenic bacteria.
I am afraid that your source was unduly influenced by the popular literature. Besides, there is no reason to have anchor worms in your pond. Proper quarantine procedures should prevent their introduction. Proper treatment should remove them permanently.
Wait until the water temperature reaches and stays above 68 degrees Fahrenheit (20 degrees Celsius). Then use trichlorfon in four treatments, each seven days apart. Be sure to use the proper dose as described on the package instructions. Measure carefully, and wear protective gloves and a dust mask.
Despite what you may have heard, there are no effective prophylactic treatments that can be applied during the winter season. You have to wait until the parasites become active in warm water.
A Tip for Pondkeepers
Many of the letters I receive ask if there is some single tip that I can pass along that will greatly simplify the task of caring for pond fish and make the task of pondkeeping more enjoyable. I think there is.
Whenever I speak to hobbyists I strongly recommend that they read AFI cover to cover. It is a mistake just to read the pond section. There is a tremendous amount one can learn from other areas of the fishkeeping hobby. When you skip over an article on marine tanks, or catfish, or whatever, you may be skipping over some important insights into your own fishkeeping problems and practices.
For example, I urge you to go back to the September 1992 issue of AFI and read Terry Siegel’s very intelligent article, “The Marine Aquarist.” As you do, just substitute “pond” for marine tank and “pond fish,” “koi,” or “goldfish” where marine animals are mentioned. If you think about Terry’s arguments about what are the keys to success with saltwater aquariums, you will learn some very important and practical lessons about successful pondkeeping.