update, good news and bad news.
good news: all 6 barbs (4 lemons, 2 red tinfoils) are eating like crazy and growing rapidly now. they are in a real growth spurt. all are wolfing down tetra cichlid sticks until they swell up like balloons.
bad news: the redhooks are not getting much food at all now. I will have to see if I can still keep them or not. if they learn to be more aggressive at eating then they will be fine. if not, I will have to sell them, I won't let them waste away.