All fresh water bodies have some degree of dissolved salts from trace amounts to the dead sea. So actually it is natural.
As does all tapwater, in trace amounts. those amounts are for the most part so small that it shouldn't be considered in the same argument as dumping one tablespoon per 5 gallons of salt in a tank. There is almost no water on the earth that doesn't contain trace amounts of salt, and 1 tblsp per 5 gallons is way way beyond trace amounts.
can understand the concerns, but over the years I have not found that water changes have had any effect on fungal problems in tanks in my area, but I have found salt to be very effective.
You might try chlorine ??? it whould reduce/ eliminate the bacteria and fungus and then can be easily removed unlike salt. Chlorine is one of several reasons why we don't have to worry about bacteria and fungus at dangerous levels from our taps. Secondly, healthy fish are naturally defensive against bacteria and fungus, these are actually almost always present in our tanks, and bacteria and fungus are limited by wealth of factors in our systems. It may be that the tap in your area delivers high levels of bacteria and fungi, but that does not mean you need to put them in your tank alive. What do you do with or for your drinking water?
Whether or not you use salt is your choice, but if bacteria and fungus are your true concern there are plenty of other ways to deal with them, and skip the salt.
BTW, about the bacteria getting through the slime layer... I don't know. I don't see how that makes any difference what thickness the layer is. If it's a problem bacteria, then it would be a problem either way... I don't even know if salt does thicken the slime layer. i have heard this, but I have my doubts. With fungus, at least, it seems to have little to do with the slime layer.
You make several valid points here.
If your fish are healthy, they should be able to defend themselves against bacteria and fungus, if they aren't healthy, the root problem should be found and worked with. no matter how much slime coat they have or shed, unhealthy fish are still succeptable to fungal and bacterial problems. On the contrary, healthy fish will heal wounds, without any sign of secondary infections.
I have also heard that it thickens slime layer, and at other times I have heard that it helps fish to shed slime layer more quickly. Either way, Fish produce and shed more slime layer as a defense against irritants or disease. So although There seems to be relatively little information on the effects of salt on slime layer, it would seem at face value that any chemical that increases slime coat and shedding thereof would most likely be an irritant. A fish that is not irritated or under attack would not elicit an immune response. In a case of a damaged, or sick fish, there may be some benifits, but we are not discussing use for treatment, we are discussing long term use on healthy fish. The salt makers and sellers promote it as therapeutic, but most of the research I have done (I've been chasing this idea all week for other purposes) has indicated otherwise so far. Let's also remember that the makers of stress coat claim that aloe increases slime coat as well, and it really does, because it irritates the fish at the elevated dosage reccomended for this purpose.
I would bet you could get the same response with a whole gambit of irritating chemicals.
I have kept fish in six different versions of city water, and two different versions of untreated well water over the years. I do not and have never used salt in my tanks (except for short term treatment of a problem) and the only time I have ever seen a bacterial of fungal infection on my fish was one occasion when I put my fish through extreme nitrite stress. I have had many injured fish over the years which healed up fine on their own.
dave
