The fullness of the tentacles are not a real indicator of good health. The area you want to focus on is the center of the pallet which is the mouth, tight and closed is a great sign of health, droopy and if you can see through the hole that is a sick one. When feeding if the BTA takes to krill (fresh) with fast reaction time thats a good sign eating at all is a great sign. The foot (base) needs to have a bright pink color and securely attached if it has signs of color change to a grey or white thats a bad sign or if it floats thats a sign of torn foot which is usually a death sentence, your BTA's color seems a little dark, is it a rose tip?