So I haven't been on this fourm in about a year, and several new care methods seem to have been adopted in my absense. The most obvious to me is the abandonment of aquarium salt on a regular basis. A year ago, there were only a few members that blew the whistle about it causing internal damage over time. However, it seems like almost everyone agrees now. I've used aquarium salt for years, and I haven't had problems. I don't use much, a pinch or so to keep the water less favorable for bacteria. My oldest fish is 3.5 years, and she seems just fine. I'm really not wanting to stop using the salt because I've had really good luck with my fish. So basically, what break through has there been to without a question link aquarium salt with internal damage? Thanks!
Fresh water fish are not designed to be in salt. Fresh water "in the wild" has an almost negligible salt content and there fore the fish aren't adapted to dealing well with salt.
I'm writing an article on the uses of salt so I won't go into much more detail. If you've got something that works for you that's fine, but chances are its not the salt that's keeping your fish healthy but the level of care you are providing them.
I understand it as cajunamy does. Prolonged use of salt makes a fish immune to its healing abilities. The more someone or something is exposed to a medication, the less useful it becomes. Maybe.... the small amounts your using isn't great enough to effect the fish? Have you had to use full doses to treat a fish and had sucess? I never use it in my tanks as preventative but I know.many who put a small cup of it in their tanks to dissolve naturally in cichlids tanks.
Byron from this forum gave info about the damage salt can do in the aquarium:
"Salt is detrimental to freshwater fish and plants in varying degrees. To understand why, we must understand what salt does in water.
Salt makes the water more dense than the same water without salt. The aquarium contains water. The bodies of fish and plant leaves also contain water [just as we do--we are, what is it, 70-some percent water?]. The water in the aquarium and the water in the fish/plant are separated by a semi-permeable layer which is the cell. Water can pass through this cell. When either body of water is more dense, the other less-dense body of water will pass through the membrane to equalize the water on both sides.
Water is constantly passing through the cells of fish by osmosis in an attempt to equate the water inside the fish (which is more dense) with the water in the aquarium. Put another way, the aquarium water is diluting the fish's body water until they are equal. Freshwater fish regularly excrete this water through respiration and urination. This is the issue behind pH differences as well as salt and other substances. It increases the fish's work--the kidney is used in the case of salt--which also increases the fish's stress in order to maintain their internal stability. Also, the fish tends to produce more mucus especially in the gills; the reason now seems to be due to the irritant property of salt--the fish is trying to get away from it.
I have an interesting measurement for fish. Dr. Stanley Weitzman, who is Emeritus Research Scientist at the Department of Ichthyology of the Smithsonian Institute in Washington and an acknowledged authority on characoid fishes, writes that 100 ppm of salt is the maximum for characins, and there are several species that show considerable stress leading to death at 60 ppm. 100 ppm is equal to .38 of one gram of salt per gallon of water. One level teaspoon holds six grams of salt, so 1 tsp of salt per gallon equates to more than 15 times the tolerable amount. Livebearers have a higher tolerance (mollies sometimes exist in brackish water) so the salt may be safe for them.
Plants: when salt is added to the aquarium water, the water inside the plant cells is less dense so it escapes through the cells. The result is that the plant literally dries out, and will wilt. I've so far been unable to find a measurement of how much salt will be detrimental to plants; all authorities I have found do note that some species are more sensitive than others, and all recommend no salt in planted aquaria. "