Here's how it goes at an LFS-you have to be a generalist. Where I worked, everyone had a different area of expertise, and we worked together. If you throw 8 types of Madagascan cichlids in front of me, I wouldn't know which way is up. If you want to build a relationship with a store (which I guarantee pays off in the end) it takes a little give and take (and not taking as in ripping off). I learned a ton of fish wisdom from customers when I worked there, but I guarantee my general knowledge about the store trumped all. On the cory cat response-It really is a pain when you get a shipment of 10 types of corys in and a couple of labels get switched around.
One more thing before I get off my box... If someone has something you want, don't feel entitled to it. It's a hard living running/working for a LFS. Give these people the money they ask for what you want without the BS. This seemingly innocent thing has got me kinda steamed...