Dude, this just my personal experience (I'm a newby) but with my BTAs I've noticed differing reaction to feeding that I'd like to share with you. I think in the end you will have to make up your own feeding habits and food choices, but these are my experiences.

When I feed the mysis or tiny chunks of food for the fish... I used to jet (gently) a baster full of foodstuff to the BTAs. They would then shrink and look all shrivelled up while getting the food into their maws.

Now when I feed a single chunk (I cut a large scallop three ways, one being decidedly smaller than the other two) to them, they gobble it up (probably before the skunks can eat too much of it) and presto a moment later they are expanded and enjoying the artificial sunlight I paid so much for. So this morning (I've been feeding them the scallop and shrimp bits for a few months now) while feeding the LPS nightwalkers I decided to feed BTA1 a single jet of particulate matter for their enjoyment. Now BTA1 is all shriveled up and digesting its food.

I don't know what the creature is thinking but if its appearance is any indication as to its disposition I would argue that they prefer their meals much like I like mine. A good solid steak as opposed to a bunch of little bits on a skewer.

Others have way more experience in dealing with these guys than I do so if anyone of them chimes in I would listen to them over what I've just typed up.

Additionally, if you go my route (see above) be sure you take into account the nutritional values needed by the anemone as opposed to just giving it the same thing over and again.

I think (remember newby here) that your bta looks good and with astute care on your part he/she will pull through nicely.