the shrimp part was a bit confusing. I don't think CBS are aggressive? Tho i think what she had was a bumble bee shrimp.
Yeah, I'm quite sure that they weren't eating the young of the other species. Their morphology pretty much makes it a physical impossibility, and they don't really have behavioral adaptations for predation of anything that can actively swim or crawl away.
Also believe that copper risk from food is overblown.