I have a breeding pair of BC's. I have had them for about 1.5 years now. I keep an assortment of shrimp in my tank and have never had my cardinals eat them. I can hardly get them to eat krill at feeding times. However they love mysis shrimp with a passion. I beleive that they would eat them if left without food for weeks on end, but if regularly fed you should have no problems. The shrimp would just be to big, and the BC would not be hungry enough to attempt to eat it.