my lfs told me I feeding my bubble tip anemone will encourage it eat other fish, that I should let feed on the stuff floating in the water. Is this true or just bad advise
Anemones will eat anything that gets caught in their tentacles including most fish and shrimp but... you cant train an anemone to eat certain foods either, so feeding it is good for it but it has no greater chance of eating fish than it did before.
The opposite of what your LFS said is actually true. If you don't feed your anemone it will be more likely to catch & eat a fish. An anemone that has been fed will not attempt to eat again for a day or two.
i guess i dont have that much experience with them.