I just bought a $3 baby green terror from either petco or petsmart, i forget which... and he'll probably be dead tomorrow because he was struggling today. I broke my own rule about not ever getting fish from either of those stores.
a lot of people on this site bash on chain petstores about having bad fish but everytime i read a story about it it begins with 'oh i saw this poor half dead fish so i decided to buy it...'
try buying the healthier fish guys and youll have better luck. even your lfs have die off so i dont get what the big deal is about buying from chain stores.
-shrug-

it ate all coral/anomme it ate my snails and one of my damsels and my clown fish
(i had it only two month i got it for 40bucks, man i was will to give it away for free that i hated that thing so much!) my my second worst purchase was a electric blue crayfish about 5-6inches long it attacked attaked every fish even over a foot long -damn thing got a deaf wish or somthing going after my RTC that thing eats any thing. 3rd is a saleleant worm it can breath air. Picking it up off the ground every moring for 3 month was a pain in the butt.