Curiously I rarely have ever had disease or parasites such as ick
Water changes, good care, current, reasonable stocking, good food etc.

So I have not used salt or MG for decades.........plants also seem to prevent ick, I've added ick infested fish, moderately so, not covered and about to die...........to planted tanks and watched them recover without treatment of any sort.

A good habitat for your fish= Healthy fish= best defense

Seems to hold much more true for plants and fish than all the baloney in the world about algicides and fish tonics, snake oils and cure alls.

Yet much less discussion, much less effort and consistency is placed on the basics of aquarium keeping for some reason. Seems some folks still believe a pound of cure is worth more than an ounce of prevention.

Why?
Because it's what folks want to hear, not the truth or the root cause.
Folks get lazy and slack off. Folks see an issue and use a pill rather than general environmental improvement.

I get folks haggling with me all the time over not doing water changes and the basic work that goes along with the hobby. Yes, it can be done but there are trade offs and folks do not think those trade offs apply to them, they think they can find ways around it and get all hard headed.

Well that is fine, but when you kill your fish, do not say I did not tell you so, and statistically speaking, most will kill some fish by avoiding it, everyone I know that's done this has..........

Just a matter of time.
Best to stay on top of things, make things simple and easy to care for, much better than salting the water.

Disease is very much like algae in this regard.

Regards,
Tom Barr