You are going to have to get them to eat something a little more substantial and less messy than that.Try breaking up small bits of pellet and mix it in with the BS.Bloodworms might be a better food than the brine shrimp and the pellet trick can be tried with them as well.
You've just bought them and are asking what to feed them yet I see you've put three for sale already on the classifieds?! Any prospective buyer will want to know what you're feeding them