http://www.algone.com/salt_in_fresh.php
In Summary:
Salt does interfere with the
osmotic regulation of fish and plants. It should be left alone;
nature regulated that part itself, by creating freshwater, brackish and saltwater fish.
The low beneficial amount of salt, mentioned above will not have any benefits in addition to water conditioners and/or stress coats already used for water treatments.
It is good to know about the benefits of salt and the understanding of the mechanisms involved. It comes in handy, should the
nitrites get out of control or as possible treatment for parasites (salt bath). A first aid kid, for sure.
And last, disease prevention and cure. This is largely if not mainly based on enhancing the slime coat or regulatory osmotic control, but again stress protecting additives and water conditioners have the same effect.
Parasite prevention? Yes - in theory. But it is not justified. The long-term use of salt in the aquarium will have more negative aspects then benefits. Use of salt as a first aid tool should be determined on an individual basis, as there are no real guidelines on how to use it safely and effectively.
The immediate threat of salt to fish and plants is greater then that of any potential long term benefits that may or may not be gained by its use.
. The intent of this article is an objective look of the effects of salt and should only be viewed as a discussion about the topic.