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.
Fish can live in water with a wide range of pH, from about 4 to 10. However, rapid changes in pH can kill fish, even within this range. While fish can adjust their body chemistry to different environmental pH values, this takes energy which could otherwise be used for growth and reproduction.