Agreed, I feel PetsAtHome sometimes get a rough ride. At the end of the day, they're all under the same name, but the care of the fish is down to the individual store managers.
Some are well run, some are not. Some have knowledgeable staff, some don't. Just make sure you go into the shop with an idea of what you want to buy, and knowing what signs to look for when checking for disease and you shouldn't go too far wrong hopefully.
Definitely agree with waterdrop, if your instincts tell you to steer clear then just don't buy from them. And always remember that alot of petsathome branches run off of one central filtration system. You may want to check with your local store. But even if the fish you're buying look healthy, if there is a diseased tank (even if they're being treated and are in quarentine), be aware if they were or are on the same filtration system then all of the tanks may be infected.
