Not to bash companies here, but I am an employee of the original store you applied for. There are actually a lot of good people that come in and out to work there... usually they end up frustrated and quitting because it's like swimming upstream. You can talk all day about proper cycling and the care of fish and animals and maybe because it's such a big store.. you don't really always attract customers who care, whereas I am usually impressed with my fellow consumers when they are shopping at a few of my favorite smaller stores. It is always a pleasure when they do care, but most just want something right then and there because it looks cool. Not to say I don't have my fair share of incompetent coworkers.
You can only do so much when it comes to denial of service, and most of your managers will intervene and take the customers side unless the situation is very dire.
Not to mention.. working in pet care isn't like how most picture it. You go long periods as the only employee in the department some days and it involves a lot more than fish. You have animals in the back and front, the ones on the floor and then the fish thrown in. You get very limited time that's uninterrupted to care for them, so it's no wonder there are usually dead fish in the tanks.
I hope you get a job soon. I know how it is and it's agonizing. Now I usually wish I had the day off.. but then when I'm at home I go insane from boredom. Haha.
Good to know you want to do well by the animals, though. +1.