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.
Further field studies have been required by the EPA (16). Direct application of copper sulfate to water may cause a significant decrease in populations of aquatic invertebrates, plants and fish (17).   Effects on Aquatic OrganismsHello I just edited this answer Copper sulfate is very toxic to fish.