i just got back from petco a few hours ago, some of the people i've bought fish from there have been very knowledgable and helpful and i've never seen any seriously sick fish. today all their oscars had what looked like ich only way too large and 10x worse. anyway i bought 3 neon tetras and 3 blue leg hermit crabs, the guy who bagged them(i snagged him from the reptile section) got me 2 sickly neons(my fault, i didn't watch and comment) then when he went to get my 3 hermit crabs he dumped the first one STRAIGHT INTO THE BAG WITH THE TETRA!!! he asked me how long they would be in the bag then when i told him 20min he pulled the hermit out and put it back in the SW tank it came from, then muttered something about doing it with SW fish to treat ich(which isn't normally done anymore and is never done to inverts) anyway he re-bagged the hermits in SW. i thought everything was ok until i got home and tested the salinity of the bag. i had planned to aclimate the hermits down to 1.018(the current salinity of my BW tank) over the course of a day or so like i did last time, when i tested the water the salinity was 1.014!!! the SOB topped off the bag w/ FW, enstead of a gentle acclimation like i planned i had to drop the hermits straight into my tank. lucky for me the hermits which looked half dead perked up immediately and look like they're going to be ok. lesson learned- always watch the guy when he/she is bagging your fish.