My daughter had one that ate great from the minute she brought him home. He ate krill at the LFS, so she took a chance with him. He was only $20.00 and thought that not too big of a risk. "Willbur" was her pride and joy until she introduced a tang to the tank without quaranteening it first. It broke out in "ick" and so did Willbur. Willbur did not survive the copper treatment the tang did. So, you can get lucky and get one that eats well, but just remember they are very prone to ick and don't do well in copper. Also look for one who's tummy is not concave or sunken in.........and is eating at the LFS. Here's a pic of "Willburr" Good luck!
Janey