Every time I go to the super Walmart in my town, I see dirty fish tanks with dead fish. In the shrimp tank, ghost shrimps are feeding on dead tank mates. In the snail tank, there are more snail shells than actual snails. I don't think Walmart hired anyone who knows how to take care of the fish, but I guess they don't really care because they get those fish for really cheap. They sell live fish like a product instead of live things.
I also heard that PetSmart and Petco are not great at taking care of their pets either, especially fish. I've never had an experience with them on live pets though, since none of them exist in my town, and I only bought equipments from them online.
In my opinion, mom and pop shops are much better at taking care of their animals, and they are also easier to get to personally know the customers.
Although I did have one bad experience when I was at Buffalo NY, where a shop owner didn't even bother to explain to the newbie me how to take care of fish, and sold me a water pump while I thought it was a filter.
What is your opinion on chain stores selling pets?