Invert Safe Marine Ich Medication/Solution?

[ThRoewer]

Sometimes you get an outbreak that just doesn't succeed in reproducing. A few bumps on one fish, and then nothing more ever, with no treatment whatever. OTOH, and with no difference in presentation, a few bumps on one fish rapidly turns into a tankwide disaster. Some of it probably has to do with the health and reproductive vigor of the ich specimens, some of it to the general health and water quality of the tank, plus species involved. It's a complex question involving a significant risk of bad outcome.

I usually have the first - ich going away (or rather the fish developing enough immunity against it to not get sick).
The latter case (tank wide outbreak) usually indicates that there is an underlying issue in the tank or that the fish are stressed or weakened by other factors.
It has nothing to do with the strength of the ich strain - Burgess has shown that pretty well in his immunization experiments.

I had cases where some fish got sick and worse with every wave while others in the same tank were immune and completely unaffected.