This confused the hell out of me because she listened to me before. Then she said that when she mentioned how nice and helpful I was to the girl at the register, she said that yes, I was, and that was good for a 'new' person.
So, yeah, there went my credibility. I spent twenty damn minutes talking her down, because yes, I do happen to know what I'm talking about. Honestly, people get annoyed with me when I say I'm not sure, but hey, I tell it like it is.
The thing you had was a filter, lady. A really crappy one. The motor on the air pump that powered it was broken, and your fish were looking pathetic. I can tell you that they weren't doing that well before because those filters? Suck. (Just like undergravel filters. Let's burn that isle and pretend they don't exist, okay?)
The new one I gave you doesn't make a whole lot of bubbling in the water. You can buy an air pump and air stone to make bubbles, but christ, woman, a filter is far more important. I'd definitely recommend having both, for various reasons, of which oxygenation is one, yes, but if you're going to stick to one? Go with the goddamn filter. It's the most basic, and most important thing you can have in your tank, and it will help get oxygen into the water.
On the up-shot, at least she did start listening to me. Eventually.