When you have an employer group health plan and want to apply for Medicare, the work status of the policy holder (you or your spouse) affects whether or not you will be in a Coordination of Benefits period.
Copper is an excellent treatment for saltwater ich or marine velvet disease, but it can be toxic and stressful to fish. Of course, using it is much better than letting a fish die from velvet, but it should never be used in a tank with healthy fish. Improper nutrition is also a commonly overlooked stressor of fish.
Today we recognize that the health of any living organism is directly related to the level of stress inflicted upon it; for fish this is a major problem because the fish cannot do anything to reduce or eliminate it they can only fight it or succumb to it.