Thanks for that--don't really appreciate being called ignorant after 30 years of fishkeeping...
"Now for the biggie, urban myth #3 (with subsections a, b, c, d, and e – for my convenience): “You should always add x amount of salt to your tank water.” The quantity “x” can vary with the poster and the local mythology, but generally is on the order of one tablespoon per five gallons. Note: this advice may be given with no questions asked about water hardness, nature of the fish kept, presence or absence of live plants, or actual water volume of the tank. This is presented as one of the great revealed truths about captive fish husbandry, universal, rarely if ever qualified or restricted, and eminently suitable for carving in stone over the door of your fish room. It slices, it dices, it chops, and your fish will live happily forever and ever. If you detect a trace of sarcasm, you begin to understand my attitude toward such edicts."