You want to do the right thing? Forget this PR stunt. Try actually training your employees on the products they sell. You'd gain a lot more credibility through the aquaria hobbyist market if your store associates were able to recommend appropriate stocking levels and compatible community mixes, or even have some sort of idea on identifying disease/illness. I know there are some employees with a decent amount of knowledge, but they are certainly in the minority. You state that one of the driving forces behind this effort is increasing fish health - by properly training employees on species compatibility, care and maintenace, and enabling them to pass that information on to potential customers, you will do worlds more good than simply removing a handful of low-markup products from your shelves.