it's probably not hungry. Mine has done the same. My bta wouldn't eat for a couple of weeks. I only feed it mysis though. Silversides are generally thought of as not good for a BTA because they're too big for them to digest. I only feed mine once a week at the most. It usually picks up the left overs from food the fish miss too. So between the mysis and the left overs, i think my BTA is getting enough. I know there's others on here that do very similar type feedings.
I wouldn't be worried. BTA's are funny and will get into moods like this.