IME BTA's kept under good lighting will not eat every time you feed them...with clowns in the tank I think they keep it well enough fed that it isn't "hungry", so to speak...BTA's (and many others) may "take" the food (ie. nematocysts fire), but they don't eat is, but rather let it float away...generally in a healthy specimen this is because they are still digesting the last meal...once they expel the waste from that meal, they will be ready to accept new food offered.