What type of lighting do you have?
I've got a BTA that I have yet to feed. There are alot of different opinions on this topic but I'm going with Melosu and Ziggy who both say no need to target feed. As long as you have good lighting you can get away with just letting him grab food from the water column. Just like he does in nature.
This morning, I fed the tank mysis and I DEF saw the BTA catch some. Like 2 hours later he shrunk up and expelled something out of his mouth. so, I think he ate
Now, almost 3 hours later, he finally reopened completely.
Others, however, target feed these guys with Silversides.