I actually work at Petco, and I've recently undertaken the fish department since the other guy left. And it was a massive undertaking.
What a lot of people don't realize is how hard it really is to maintain this many fish with the supplies we're given. We have no quarentine tanks, inadaquate store use food, inadequate means of treating illnesses, and abyssmally overcrowded tanks. Not to mention our protein skimmers don't even work and WE DON'T EVEN HAVE A FREAKING RO UNIT!!! This is corperate America at work for you. My hands are pretty much tied when saltwater gets ick, which is often. With no QT tanks I'm left to do low-salinity "dips" with specimen cups contantly which presents a whole new array of problems itself. Our store manager couldn't even help me out if he wanted to, this is all BS from the higher-ups. We are literally screwed.
That doesn't mean our department isn't well-kept, but it takes absolutely every single one of my 35 hours or so in a workweek to keep them alive. Seriously, the corperate managers cut us no breaks as far as resources. I'm constantly juggling between sick fish, helping customers, keeping my department clean and organized, doing water changes, and a multitude of other issues.
Another thing people don't realize is that most of the employees at a place like Petco or Petsmart are barely making more than minimum wage, and getting raises is not easy. So hiring a marine biologist at $8.50 an hour is pretty heinous to expect. Any given store is lucky to even have one or two people that have any idea what they're talking about. We have one or two people per type of animal that are great and can explain things well, the rest are basically work horses. And going there when one of those people are there is a hit-or-miss. Luckily for our Petco, our old fish guy was suffering economic problems and was forced to get a job there. He made aquatics into a brand new department and knew anything our customers could've needed to know. We were told we had one of the best aquatic departments in the entire company, actually. But now I'm maintaining everything and it's beyond brutal. This is around 1260 gallons in fish tanks (including sumps) with equipment that isn't up date.
All I'm saying is, don't hate the individual store. Hate the company as a whole. I personally think fish stores should be kept seperate from regular pet stores, because there is a lot more to know and a lot more maintainence neccesary for fish than hamsters or snakes.